diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..491deae
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,7 @@
+version: 2
+updates:
+- package-ecosystem: pip
+  directory: "/"
+  schedule:
+    interval: daily
+  open-pull-requests-limit: 10
diff --git a/README.md b/README.md
index acd448b..d642445 100644
--- a/README.md
+++ b/README.md
@@ -102,3 +102,8 @@ poetry install
 - Keep it simple. Run `poetry run black` to auto format the code.
 - Test your changes locally by running `poetry run pytest` (pass `--cov --cov-report html` for browsable coverage report).
 - If you are familiar with [tox](https://tox.readthedocs.io), you may want to use it for testing in different python versions.
+
+Alternatives
+------------
+
+- [environs](https://github.com/sloria/environs) - simplified environment variable parsing.
diff --git a/expandvars.py b/expandvars.py
index 0f3254a..5d00fa5 100644
--- a/expandvars.py
+++ b/expandvars.py
@@ -8,7 +8,7 @@
 __email__ = "sayanarijit@gmail.com"
 __homepage__ = "https://github.com/sayanarijit/expandvars"
 __description__ = "Expand system variables Unix style"
-__version__ = "v0.6.5"  # Also update pyproject.toml
+__version__ = "v0.7.0"  # Also update pyproject.toml
 __license__ = "MIT"
 __all__ = [
     "BadSubstitution",
@@ -392,7 +392,7 @@ def expand_default(var, vars_, set_, nounset, indirect, environ, var_symbol):
     for c in vars_:
         if c == "}":
             n = len(default) + 1
-            default_ = "".join(default)
+            default_ = expand("".join(default))
             if set_ and var not in environ:
                 environ.update({var: default_})
             return getenv(
diff --git a/poetry.lock b/poetry.lock
index 1119ae3..6f3e212 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1,409 +1,238 @@
 [[package]]
-category = "dev"
-description = "A small Python module for determining appropriate platform-specific dirs, e.g. a \"user data dir\"."
 name = "appdirs"
+version = "1.4.4"
+description = "A small Python module for determining appropriate platform-specific dirs, e.g. a \"user data dir\"."
+category = "dev"
 optional = false
 python-versions = "*"
-version = "1.4.4"
 
 [[package]]
-category = "dev"
-description = "Atomic file writes."
 name = "atomicwrites"
-optional = true
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 version = "1.4.0"
-
-[[package]]
+description = "Atomic file writes."
 category = "dev"
-description = "Classes Without Boilerplate"
-name = "attrs"
-optional = true
+optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "19.3.0"
-
-[package.extras]
-azure-pipelines = ["coverage", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface", "pytest-azurepipelines"]
-dev = ["coverage", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface", "sphinx", "pre-commit"]
-docs = ["sphinx", "zope.interface"]
-tests = ["coverage", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface"]
 
 [[package]]
+name = "attrs"
+version = "20.3.0"
+description = "Classes Without Boilerplate"
 category = "dev"
-description = "Backport of functools.lru_cache"
-marker = "python_version < \"3.2\""
-name = "backports.functools-lru-cache"
-optional = true
-python-versions = ">=2.6"
-version = "1.6.1"
+optional = false
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
 [package.extras]
-docs = ["sphinx", "jaraco.packaging (>=3.2)", "rst.linker (>=1.9)"]
-testing = ["pytest (>=3.5,<3.7.3 || >3.7.3)", "pytest-checkdocs (>=1.2.3)", "pytest-flake8", "pytest-black-multipy", "pytest-cov"]
+dev = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface", "furo", "sphinx", "pre-commit"]
+docs = ["furo", "sphinx", "zope.interface"]
+tests = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface"]
+tests_no_zope = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six"]
 
 [[package]]
-category = "dev"
-description = "Cross-platform colored terminal text."
-marker = "sys_platform == \"win32\" and python_version == \"3.4\""
 name = "colorama"
-optional = true
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 version = "0.4.1"
-
-[[package]]
-category = "dev"
 description = "Cross-platform colored terminal text."
-marker = "sys_platform == \"win32\" and python_version != \"3.4\""
-name = "colorama"
-optional = true
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
-version = "0.4.3"
-
-[[package]]
 category = "dev"
-description = "Updated configparser from Python 3.7 for Python 2.6+."
-marker = "python_version < \"3\""
-name = "configparser"
 optional = false
-python-versions = ">=2.6"
-version = "4.0.2"
-
-[package.extras]
-docs = ["sphinx", "jaraco.packaging (>=3.2)", "rst.linker (>=1.9)"]
-testing = ["pytest (>=3.5,<3.7.3 || >3.7.3)", "pytest-checkdocs (>=1.2)", "pytest-flake8", "pytest-black-multipy"]
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
 [[package]]
+name = "colorama"
+version = "0.4.4"
+description = "Cross-platform colored terminal text."
 category = "dev"
-description = "Backports and enhancements for the contextlib module"
-marker = "python_version < \"3.4\""
-name = "contextlib2"
 optional = false
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "0.6.0.post1"
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
 
 [[package]]
-category = "dev"
-description = "Code coverage measurement for Python"
 name = "coverage"
-optional = true
-python-versions = "*"
 version = "4.4.2"
-
-[[package]]
-category = "dev"
-description = "Code coverage measurement for Python"
-name = "coverage"
-optional = true
-python-versions = ">=2.6, !=3.0.*, !=3.1.*, !=3.2.*, <4"
-version = "4.5.4"
-
-[[package]]
-category = "dev"
 description = "Code coverage measurement for Python"
-name = "coverage"
-optional = true
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, <4"
-version = "5.2.1"
-
-[package.extras]
-toml = ["toml"]
-
-[[package]]
 category = "dev"
-description = "Distribution utilities"
-name = "distlib"
 optional = false
 python-versions = "*"
-version = "0.3.1"
 
 [[package]]
+name = "distlib"
+version = "0.3.1"
+description = "Distribution utilities"
 category = "dev"
-description = "A platform independent file lock."
-name = "filelock"
 optional = false
 python-versions = "*"
-version = "3.0.12"
 
 [[package]]
+name = "filelock"
+version = "3.0.12"
+description = "A platform independent file lock."
 category = "dev"
-description = "Python function signatures from PEP362 for Python 2.6, 2.7 and 3.2+"
-marker = "python_version < \"3.0\""
-name = "funcsigs"
-optional = true
+optional = false
 python-versions = "*"
-version = "1.0.2"
 
 [[package]]
-category = "dev"
-description = "Read metadata from Python packages"
-marker = "python_version < \"3.8\""
 name = "importlib-metadata"
+version = "0.23"
+description = "Read metadata from Python packages"
+category = "dev"
 optional = false
 python-versions = ">=2.7,!=3.0,!=3.1,!=3.2,!=3.3"
-version = "0.23"
 
 [package.dependencies]
+pathlib2 = {version = "*", markers = "python_version == \"3.4.*\" or python_version < \"3\""}
 zipp = ">=0.5"
 
-[package.dependencies.configparser]
-python = "<3"
-version = ">=3.5"
-
-[package.dependencies.contextlib2]
-python = "<3"
-version = "*"
-
 [package.extras]
 docs = ["sphinx", "rst.linker"]
 testing = ["packaging", "importlib-resources"]
 
 [[package]]
-category = "dev"
-description = "Read resources from Python packages"
-marker = "python_version < \"3.7\""
 name = "importlib-resources"
-optional = false
-python-versions = ">=2.7,!=3.0,!=3.1,!=3.2,!=3.3"
 version = "1.0.2"
-
-[package.dependencies]
-[package.dependencies.typing]
-python = "<3.5"
-version = "*"
-
-[[package]]
-category = "dev"
 description = "Read resources from Python packages"
-marker = "python_version < \"3.7\""
-name = "importlib-resources"
-optional = false
-python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,>=2.7"
-version = "3.0.0"
-
-[package.dependencies]
-[package.dependencies.contextlib2]
-python = "<3"
-version = "*"
-
-[package.dependencies.pathlib2]
-python = "<3"
-version = "*"
-
-[package.dependencies.singledispatch]
-python = "<3.4"
-version = "*"
-
-[package.dependencies.typing]
-python = "<3.5"
-version = "*"
-
-[package.dependencies.zipp]
-python = "<3.8"
-version = ">=0.4"
-
-[package.extras]
-docs = ["sphinx", "rst.linker", "jaraco.packaging"]
-
-[[package]]
 category = "dev"
-description = "More routines for operating on iterables, beyond itertools"
-marker = "python_version <= \"2.7\""
-name = "more-itertools"
-optional = true
-python-versions = "*"
-version = "5.0.0"
+optional = false
+python-versions = ">=2.7,!=3.0,!=3.1,!=3.2,!=3.3"
 
 [package.dependencies]
-six = ">=1.0.0,<2.0.0"
+typing = {version = "*", markers = "python_version < \"3.5\""}
 
 [[package]]
-category = "dev"
-description = "More routines for operating on iterables, beyond itertools"
-marker = "python_version > \"2.7\""
 name = "more-itertools"
-optional = true
-python-versions = ">=3.4"
 version = "7.2.0"
-
-[[package]]
-category = "dev"
 description = "More routines for operating on iterables, beyond itertools"
-marker = "python_version > \"2.7\""
-name = "more-itertools"
-optional = true
-python-versions = ">=3.5"
-version = "8.4.0"
+category = "dev"
+optional = false
+python-versions = ">=3.4"
 
 [[package]]
-category = "dev"
-description = "Core utilities for Python packages"
 name = "packaging"
+version = "20.9"
+description = "Core utilities for Python packages"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "20.4"
 
 [package.dependencies]
 pyparsing = ">=2.0.2"
-six = "*"
 
 [[package]]
-category = "dev"
-description = "Object-oriented filesystem paths"
-marker = "python_version < \"3.4\" and sys_platform != \"win32\" or python_version < \"3.6\""
 name = "pathlib2"
+version = "2.3.5"
+description = "Object-oriented filesystem paths"
+category = "dev"
 optional = false
 python-versions = "*"
-version = "2.3.5"
 
 [package.dependencies]
+scandir = {version = "*", markers = "python_version < \"3.5\""}
 six = "*"
 
-[package.dependencies.scandir]
-python = "<3.5"
-version = "*"
-
 [[package]]
-category = "dev"
-description = "plugin and hook calling mechanisms for python"
 name = "pluggy"
+version = "0.13.1"
+description = "plugin and hook calling mechanisms for python"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "0.13.1"
 
 [package.dependencies]
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = ">=0.12"
+importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
 
 [package.extras]
 dev = ["pre-commit", "tox"]
 
 [[package]]
-category = "dev"
-description = "library with cross-python path, ini-parsing, io, code, log facilities"
 name = "py"
+version = "1.10.0"
+description = "library with cross-python path, ini-parsing, io, code, log facilities"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "1.9.0"
 
 [[package]]
-category = "dev"
-description = "Python parsing module"
 name = "pyparsing"
+version = "2.4.7"
+description = "Python parsing module"
+category = "dev"
 optional = false
 python-versions = ">=2.6, !=3.0.*, !=3.1.*, !=3.2.*"
-version = "2.4.7"
 
 [[package]]
-category = "dev"
-description = "pytest: simple powerful testing with Python"
 name = "pytest"
-optional = true
-python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,>=2.7"
 version = "4.6.11"
+description = "pytest: simple powerful testing with Python"
+category = "dev"
+optional = false
+python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,>=2.7"
 
 [package.dependencies]
 atomicwrites = ">=1.0"
 attrs = ">=17.4.0"
+colorama = [
+    {version = "*", markers = "sys_platform == \"win32\" and python_version != \"3.4\""},
+    {version = "<=0.4.1", markers = "sys_platform == \"win32\" and python_version == \"3.4\""},
+]
+importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
+more-itertools = {version = ">=4.0.0", markers = "python_version > \"2.7\""}
 packaging = "*"
+pathlib2 = {version = ">=2.2.0", markers = "python_version < \"3.6\""}
 pluggy = ">=0.12,<1.0"
 py = ">=1.5.0"
 six = ">=1.10.0"
 wcwidth = "*"
 
-[[package.dependencies.colorama]]
-python = "<3.4.0 || >=3.5.0"
-version = "*"
-
-[[package.dependencies.colorama]]
-python = ">=3.4,<3.5"
-version = "<=0.4.1"
-
-[[package.dependencies.more-itertools]]
-python = "<2.8"
-version = ">=4.0.0,<6.0.0"
-
-[[package.dependencies.more-itertools]]
-python = ">=2.8"
-version = ">=4.0.0"
-
-[package.dependencies.funcsigs]
-python = "<3.0"
-version = ">=1.0"
-
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = ">=0.12"
-
-[package.dependencies.pathlib2]
-python = "<3.6"
-version = ">=2.2.0"
-
 [package.extras]
 testing = ["argcomplete", "hypothesis (>=3.56)", "nose", "requests", "mock"]
 
 [[package]]
-category = "dev"
-description = "Pytest plugin for measuring coverage."
 name = "pytest-cov"
-optional = true
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 version = "2.8.1"
+description = "Pytest plugin for measuring coverage."
+category = "dev"
+optional = false
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
 [package.dependencies]
 coverage = ">=4.4"
 pytest = ">=3.6"
 
 [package.extras]
-testing = ["fields", "hunter", "process-tests (2.0.2)", "six", "virtualenv"]
+testing = ["fields", "hunter", "process-tests (==2.0.2)", "six", "virtualenv"]
 
 [[package]]
-category = "dev"
-description = "scandir, a better directory iterator and faster os.walk()"
-marker = "python_version < \"3\" and sys_platform != \"win32\" or python_version < \"3.5\" or python_version < \"3.4\" and sys_platform != \"win32\" and (python_version < \"3.4\" and sys_platform != \"win32\" or python_version < \"3.5\") or python_version < \"3.4\" and sys_platform != \"win32\""
 name = "scandir"
-optional = false
-python-versions = "*"
 version = "1.10.0"
-
-[[package]]
+description = "scandir, a better directory iterator and faster os.walk()"
 category = "dev"
-description = "This library brings functools.singledispatch from Python 3.4 to Python 2.6-3.3."
-marker = "python_version < \"3.4\""
-name = "singledispatch"
 optional = false
 python-versions = "*"
-version = "3.4.0.3"
-
-[package.dependencies]
-six = "*"
 
 [[package]]
-category = "dev"
-description = "Python 2 and 3 compatibility utilities"
 name = "six"
+version = "1.15.0"
+description = "Python 2 and 3 compatibility utilities"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*"
-version = "1.15.0"
 
 [[package]]
-category = "dev"
-description = "Python Library for Tom's Obvious, Minimal Language"
 name = "toml"
+version = "0.10.2"
+description = "Python Library for Tom's Obvious, Minimal Language"
+category = "dev"
 optional = false
-python-versions = "*"
-version = "0.10.1"
+python-versions = ">=2.6, !=3.0.*, !=3.1.*, !=3.2.*"
 
 [[package]]
-category = "dev"
-description = "tox is a generic virtualenv management and test command line tool"
 name = "tox"
+version = "3.14.0"
+description = "tox is a generic virtualenv management and test command line tool"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "3.14.0"
 
 [package.dependencies]
 filelock = ">=3.0.0,<4"
+importlib-metadata = {version = ">=0.12,<1", markers = "python_version < \"3.8\""}
 packaging = ">=14"
 pluggy = ">=0.12.0,<1"
 py = ">=1.4.17,<2"
@@ -411,79 +240,53 @@ six = ">=1.0.0,<2"
 toml = ">=0.9.4"
 virtualenv = ">=14.0.0"
 
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = ">=0.12,<1"
-
 [package.extras]
 docs = ["sphinx (>=2.0.0,<3)", "towncrier (>=18.5.0)", "pygments-github-lexers (>=0.0.5)", "sphinxcontrib-autoprogram (>=0.1.5)"]
 testing = ["freezegun (>=0.3.11,<1)", "pathlib2 (>=2.3.3,<3)", "pytest (>=4.0.0,<6)", "pytest-cov (>=2.5.1,<3)", "pytest-mock (>=1.10.0,<2)", "pytest-xdist (>=1.22.2,<2)", "pytest-randomly (>=1.2.3,<2)", "flaky (>=3.4.0,<4)", "psutil (>=5.6.1,<6)"]
 
 [[package]]
-category = "dev"
-description = "Type Hints for Python"
-marker = "python_version < \"3.5\""
 name = "typing"
+version = "3.7.4.3"
+description = "Type Hints for Python"
+category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "3.7.4.3"
 
 [[package]]
-category = "dev"
-description = "Virtual Python Environment builder"
 name = "virtualenv"
+version = "20.4.3"
+description = "Virtual Python Environment builder"
+category = "dev"
 optional = false
 python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,>=2.7"
-version = "20.0.31"
 
 [package.dependencies]
 appdirs = ">=1.4.3,<2"
 distlib = ">=0.3.1,<1"
 filelock = ">=3.0.0,<4"
+importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
+importlib-resources = {version = ">=1.0", markers = "python_version < \"3.7\""}
 six = ">=1.9.0,<2"
 
-[package.dependencies.importlib-metadata]
-python = "<3.8"
-version = ">=0.12,<2"
-
-[package.dependencies.importlib-resources]
-python = "<3.7"
-version = ">=1.0"
-
-[package.dependencies.pathlib2]
-python = "<3.4"
-version = ">=2.3.3,<3"
-
 [package.extras]
 docs = ["proselint (>=0.10.2)", "sphinx (>=3)", "sphinx-argparse (>=0.2.5)", "sphinx-rtd-theme (>=0.4.3)", "towncrier (>=19.9.0rc1)"]
-testing = ["coverage (>=5)", "coverage-enable-subprocess (>=1)", "flaky (>=3)", "pytest (>=4)", "pytest-env (>=0.6.2)", "pytest-freezegun (>=0.4.1)", "pytest-mock (>=2)", "pytest-randomly (>=1)", "pytest-timeout (>=1)", "pytest-xdist (>=1.31.0)", "packaging (>=20.0)", "xonsh (>=0.9.16)"]
+testing = ["coverage (>=4)", "coverage-enable-subprocess (>=1)", "flaky (>=3)", "pytest (>=4)", "pytest-env (>=0.6.2)", "pytest-freezegun (>=0.4.1)", "pytest-mock (>=2)", "pytest-randomly (>=1)", "pytest-timeout (>=1)", "packaging (>=20.0)", "xonsh (>=0.9.16)"]
 
 [[package]]
-category = "dev"
-description = "Measures the displayed width of unicode strings in a terminal"
 name = "wcwidth"
-optional = true
-python-versions = "*"
 version = "0.2.5"
-
-[package.dependencies]
-[package.dependencies."backports.functools-lru-cache"]
-python = "<3.2"
-version = ">=1.2.1"
+description = "Measures the displayed width of unicode strings in a terminal"
+category = "dev"
+optional = false
+python-versions = "*"
 
 [[package]]
-category = "dev"
-description = "Backport of pathlib-compatible object wrapper for zip files"
-marker = "python_version < \"3.8\""
 name = "zipp"
+version = "1.2.0"
+description = "Backport of pathlib-compatible object wrapper for zip files"
+category = "dev"
 optional = false
 python-versions = ">=2.7"
-version = "1.2.0"
-
-[package.dependencies]
-[package.dependencies.contextlib2]
-python = "<3.4"
-version = "*"
 
 [package.extras]
 docs = ["sphinx", "jaraco.packaging (>=3.2)", "rst.linker (>=1.9)"]
@@ -493,8 +296,9 @@ testing = ["pathlib2", "unittest2", "jaraco.itertools", "func-timeout"]
 testing = []
 
 [metadata]
-content-hash = "f5142d1677961f8b29e639703b10ce5ce6869a5a343890d41135bd8ce80e0a83"
-python-versions = "*"
+lock-version = "1.1"
+python-versions = ">=3.4"
+content-hash = "71c4795063c2bb3d0fe2ad4dc7f727021eb75e8b50b9cddcb9419ce0e883a254"
 
 [metadata.files]
 appdirs = [
@@ -506,26 +310,14 @@ atomicwrites = [
     {file = "atomicwrites-1.4.0.tar.gz", hash = "sha256:ae70396ad1a434f9c7046fd2dd196fc04b12f9e91ffb859164193be8b6168a7a"},
 ]
 attrs = [
-    {file = "attrs-19.3.0-py2.py3-none-any.whl", hash = "sha256:08a96c641c3a74e44eb59afb61a24f2cb9f4d7188748e76ba4bb5edfa3cb7d1c"},
-    {file = "attrs-19.3.0.tar.gz", hash = "sha256:f7b7ce16570fe9965acd6d30101a28f62fb4a7f9e926b3bbc9b61f8b04247e72"},
-]
-"backports.functools-lru-cache" = [
-    {file = "backports.functools_lru_cache-1.6.1-py2.py3-none-any.whl", hash = "sha256:0bada4c2f8a43d533e4ecb7a12214d9420e66eb206d54bf2d682581ca4b80848"},
-    {file = "backports.functools_lru_cache-1.6.1.tar.gz", hash = "sha256:8fde5f188da2d593bd5bc0be98d9abc46c95bb8a9dde93429570192ee6cc2d4a"},
+    {file = "attrs-20.3.0-py2.py3-none-any.whl", hash = "sha256:31b2eced602aa8423c2aea9c76a724617ed67cf9513173fd3a4f03e3a929c7e6"},
+    {file = "attrs-20.3.0.tar.gz", hash = "sha256:832aa3cde19744e49938b91fea06d69ecb9e649c93ba974535d08ad92164f700"},
 ]
 colorama = [
     {file = "colorama-0.4.1-py2.py3-none-any.whl", hash = "sha256:f8ac84de7840f5b9c4e3347b3c1eaa50f7e49c2b07596221daec5edaabbd7c48"},
     {file = "colorama-0.4.1.tar.gz", hash = "sha256:05eed71e2e327246ad6b38c540c4a3117230b19679b875190486ddd2d721422d"},
-    {file = "colorama-0.4.3-py2.py3-none-any.whl", hash = "sha256:7d73d2a99753107a36ac6b455ee49046802e59d9d076ef8e47b61499fa29afff"},
-    {file = "colorama-0.4.3.tar.gz", hash = "sha256:e96da0d330793e2cb9485e9ddfd918d456036c7149416295932478192f4436a1"},
-]
-configparser = [
-    {file = "configparser-4.0.2-py2.py3-none-any.whl", hash = "sha256:254c1d9c79f60c45dfde850850883d5aaa7f19a23f13561243a050d5a7c3fe4c"},
-    {file = "configparser-4.0.2.tar.gz", hash = "sha256:c7d282687a5308319bf3d2e7706e575c635b0a470342641c93bea0ea3b5331df"},
-]
-contextlib2 = [
-    {file = "contextlib2-0.6.0.post1-py2.py3-none-any.whl", hash = "sha256:3355078a159fbb44ee60ea80abd0d87b80b78c248643b49aa6d94673b413609b"},
-    {file = "contextlib2-0.6.0.post1.tar.gz", hash = "sha256:01f490098c18b19d2bd5bb5dc445b2054d2fa97f09a4280ba2c5f3c394c8162e"},
+    {file = "colorama-0.4.4-py2.py3-none-any.whl", hash = "sha256:9f47eda37229f68eee03b24b9748937c7dc3868f906e8ba69fbcbdd3bc5dc3e2"},
+    {file = "colorama-0.4.4.tar.gz", hash = "sha256:5941b2b48a20143d2267e95b1c2a7603ce057ee39fd88e7329b0c292aa16869b"},
 ]
 coverage = [
     {file = "coverage-4.4.2-cp26-cp26m-macosx_10_10_x86_64.whl", hash = "sha256:d1ee76f560c3c3e8faada866a07a32485445e16ed2206ac8378bd90dadffb9f0"},
@@ -568,72 +360,6 @@ coverage = [
     {file = "coverage-4.4.2.win32-py3.4.exe", hash = "sha256:ab3508df9a92c1d3362343d235420d08e2662969b83134f8a97dc1451cbe5e84"},
     {file = "coverage-4.4.2.win32-py3.5.exe", hash = "sha256:43a155eb76025c61fc20c3d03b89ca28efa6f5be572ab6110b2fb68eda96bfea"},
     {file = "coverage-4.4.2.win32-py3.6.exe", hash = "sha256:f98b461cb59f117887aa634a66022c0bd394278245ed51189f63a036516e32de"},
-    {file = "coverage-4.5.4-cp26-cp26m-macosx_10_12_x86_64.whl", hash = "sha256:eee64c616adeff7db37cc37da4180a3a5b6177f5c46b187894e633f088fb5b28"},
-    {file = "coverage-4.5.4-cp27-cp27m-macosx_10_12_x86_64.whl", hash = "sha256:ef824cad1f980d27f26166f86856efe11eff9912c4fed97d3804820d43fa550c"},
-    {file = "coverage-4.5.4-cp27-cp27m-macosx_10_13_intel.whl", hash = "sha256:9a334d6c83dfeadae576b4d633a71620d40d1c379129d587faa42ee3e2a85cce"},
-    {file = "coverage-4.5.4-cp27-cp27m-manylinux1_i686.whl", hash = "sha256:7494b0b0274c5072bddbfd5b4a6c6f18fbbe1ab1d22a41e99cd2d00c8f96ecfe"},
-    {file = "coverage-4.5.4-cp27-cp27m-manylinux1_x86_64.whl", hash = "sha256:826f32b9547c8091679ff292a82aca9c7b9650f9fda3e2ca6bf2ac905b7ce888"},
-    {file = "coverage-4.5.4-cp27-cp27m-win32.whl", hash = "sha256:63a9a5fc43b58735f65ed63d2cf43508f462dc49857da70b8980ad78d41d52fc"},
-    {file = "coverage-4.5.4-cp27-cp27m-win_amd64.whl", hash = "sha256:e2ede7c1d45e65e209d6093b762e98e8318ddeff95317d07a27a2140b80cfd24"},
-    {file = "coverage-4.5.4-cp27-cp27mu-manylinux1_i686.whl", hash = "sha256:dd579709a87092c6dbee09d1b7cfa81831040705ffa12a1b248935274aee0437"},
-    {file = "coverage-4.5.4-cp27-cp27mu-manylinux1_x86_64.whl", hash = "sha256:08907593569fe59baca0bf152c43f3863201efb6113ecb38ce7e97ce339805a6"},
-    {file = "coverage-4.5.4-cp33-cp33m-macosx_10_10_x86_64.whl", hash = "sha256:6b62544bb68106e3f00b21c8930e83e584fdca005d4fffd29bb39fb3ffa03cb5"},
-    {file = "coverage-4.5.4-cp34-cp34m-macosx_10_12_x86_64.whl", hash = "sha256:331cb5115673a20fb131dadd22f5bcaf7677ef758741312bee4937d71a14b2ef"},
-    {file = "coverage-4.5.4-cp34-cp34m-manylinux1_i686.whl", hash = "sha256:bf1ef9eb901113a9805287e090452c05547578eaab1b62e4ad456fcc049a9b7e"},
-    {file = "coverage-4.5.4-cp34-cp34m-manylinux1_x86_64.whl", hash = "sha256:386e2e4090f0bc5df274e720105c342263423e77ee8826002dcffe0c9533dbca"},
-    {file = "coverage-4.5.4-cp34-cp34m-win32.whl", hash = "sha256:fa964bae817babece5aa2e8c1af841bebb6d0b9add8e637548809d040443fee0"},
-    {file = "coverage-4.5.4-cp34-cp34m-win_amd64.whl", hash = "sha256:df6712284b2e44a065097846488f66840445eb987eb81b3cc6e4149e7b6982e1"},
-    {file = "coverage-4.5.4-cp35-cp35m-macosx_10_12_x86_64.whl", hash = "sha256:efc89291bd5a08855829a3c522df16d856455297cf35ae827a37edac45f466a7"},
-    {file = "coverage-4.5.4-cp35-cp35m-manylinux1_i686.whl", hash = "sha256:e4ef9c164eb55123c62411f5936b5c2e521b12356037b6e1c2617cef45523d47"},
-    {file = "coverage-4.5.4-cp35-cp35m-manylinux1_x86_64.whl", hash = "sha256:ff37757e068ae606659c28c3bd0d923f9d29a85de79bf25b2b34b148473b5025"},
-    {file = "coverage-4.5.4-cp35-cp35m-win32.whl", hash = "sha256:bf0a7aed7f5521c7ca67febd57db473af4762b9622254291fbcbb8cd0ba5e33e"},
-    {file = "coverage-4.5.4-cp35-cp35m-win_amd64.whl", hash = "sha256:19e4df788a0581238e9390c85a7a09af39c7b539b29f25c89209e6c3e371270d"},
-    {file = "coverage-4.5.4-cp36-cp36m-macosx_10_13_x86_64.whl", hash = "sha256:60851187677b24c6085248f0a0b9b98d49cba7ecc7ec60ba6b9d2e5574ac1ee9"},
-    {file = "coverage-4.5.4-cp36-cp36m-manylinux1_i686.whl", hash = "sha256:245388cda02af78276b479f299bbf3783ef0a6a6273037d7c60dc73b8d8d7755"},
-    {file = "coverage-4.5.4-cp36-cp36m-manylinux1_x86_64.whl", hash = "sha256:c0afd27bc0e307a1ffc04ca5ec010a290e49e3afbe841c5cafc5c5a80ecd81c9"},
-    {file = "coverage-4.5.4-cp36-cp36m-win32.whl", hash = "sha256:6ba744056423ef8d450cf627289166da65903885272055fb4b5e113137cfa14f"},
-    {file = "coverage-4.5.4-cp36-cp36m-win_amd64.whl", hash = "sha256:af7ed8a8aa6957aac47b4268631fa1df984643f07ef00acd374e456364b373f5"},
-    {file = "coverage-4.5.4-cp37-cp37m-macosx_10_13_x86_64.whl", hash = "sha256:3a794ce50daee01c74a494919d5ebdc23d58873747fa0e288318728533a3e1ca"},
-    {file = "coverage-4.5.4-cp37-cp37m-manylinux1_i686.whl", hash = "sha256:0be0f1ed45fc0c185cfd4ecc19a1d6532d72f86a2bac9de7e24541febad72650"},
-    {file = "coverage-4.5.4-cp37-cp37m-manylinux1_x86_64.whl", hash = "sha256:eca2b7343524e7ba246cab8ff00cab47a2d6d54ada3b02772e908a45675722e2"},
-    {file = "coverage-4.5.4-cp37-cp37m-win32.whl", hash = "sha256:93715dffbcd0678057f947f496484e906bf9509f5c1c38fc9ba3922893cda5f5"},
-    {file = "coverage-4.5.4-cp37-cp37m-win_amd64.whl", hash = "sha256:23cc09ed395b03424d1ae30dcc292615c1372bfba7141eb85e11e50efaa6b351"},
-    {file = "coverage-4.5.4-cp38-cp38-macosx_10_13_x86_64.whl", hash = "sha256:141f08ed3c4b1847015e2cd62ec06d35e67a3ac185c26f7635f4406b90afa9c5"},
-    {file = "coverage-4.5.4.tar.gz", hash = "sha256:e07d9f1a23e9e93ab5c62902833bf3e4b1f65502927379148b6622686223125c"},
-    {file = "coverage-5.2.1-cp27-cp27m-macosx_10_13_intel.whl", hash = "sha256:40f70f81be4d34f8d491e55936904db5c527b0711b2a46513641a5729783c2e4"},
-    {file = "coverage-5.2.1-cp27-cp27m-macosx_10_9_x86_64.whl", hash = "sha256:675192fca634f0df69af3493a48224f211f8db4e84452b08d5fcebb9167adb01"},
-    {file = "coverage-5.2.1-cp27-cp27m-manylinux1_i686.whl", hash = "sha256:2fcc8b58953d74d199a1a4d633df8146f0ac36c4e720b4a1997e9b6327af43a8"},
-    {file = "coverage-5.2.1-cp27-cp27m-manylinux1_x86_64.whl", hash = "sha256:64c4f340338c68c463f1b56e3f2f0423f7b17ba6c3febae80b81f0e093077f59"},
-    {file = "coverage-5.2.1-cp27-cp27m-win32.whl", hash = "sha256:52f185ffd3291196dc1aae506b42e178a592b0b60a8610b108e6ad892cfc1bb3"},
-    {file = "coverage-5.2.1-cp27-cp27m-win_amd64.whl", hash = "sha256:30bc103587e0d3df9e52cd9da1dd915265a22fad0b72afe54daf840c984b564f"},
-    {file = "coverage-5.2.1-cp27-cp27mu-manylinux1_i686.whl", hash = "sha256:9ea749fd447ce7fb1ac71f7616371f04054d969d412d37611716721931e36efd"},
-    {file = "coverage-5.2.1-cp27-cp27mu-manylinux1_x86_64.whl", hash = "sha256:ce7866f29d3025b5b34c2e944e66ebef0d92e4a4f2463f7266daa03a1332a651"},
-    {file = "coverage-5.2.1-cp35-cp35m-macosx_10_13_x86_64.whl", hash = "sha256:4869ab1c1ed33953bb2433ce7b894a28d724b7aa76c19b11e2878034a4e4680b"},
-    {file = "coverage-5.2.1-cp35-cp35m-manylinux1_i686.whl", hash = "sha256:a3ee9c793ffefe2944d3a2bd928a0e436cd0ac2d9e3723152d6fd5398838ce7d"},
-    {file = "coverage-5.2.1-cp35-cp35m-manylinux1_x86_64.whl", hash = "sha256:28f42dc5172ebdc32622a2c3f7ead1b836cdbf253569ae5673f499e35db0bac3"},
-    {file = "coverage-5.2.1-cp35-cp35m-win32.whl", hash = "sha256:e26c993bd4b220429d4ec8c1468eca445a4064a61c74ca08da7429af9bc53bb0"},
-    {file = "coverage-5.2.1-cp35-cp35m-win_amd64.whl", hash = "sha256:4186fc95c9febeab5681bc3248553d5ec8c2999b8424d4fc3a39c9cba5796962"},
-    {file = "coverage-5.2.1-cp36-cp36m-macosx_10_13_x86_64.whl", hash = "sha256:b360d8fd88d2bad01cb953d81fd2edd4be539df7bfec41e8753fe9f4456a5082"},
-    {file = "coverage-5.2.1-cp36-cp36m-manylinux1_i686.whl", hash = "sha256:1adb6be0dcef0cf9434619d3b892772fdb48e793300f9d762e480e043bd8e716"},
-    {file = "coverage-5.2.1-cp36-cp36m-manylinux1_x86_64.whl", hash = "sha256:098a703d913be6fbd146a8c50cc76513d726b022d170e5e98dc56d958fd592fb"},
-    {file = "coverage-5.2.1-cp36-cp36m-win32.whl", hash = "sha256:962c44070c281d86398aeb8f64e1bf37816a4dfc6f4c0f114756b14fc575621d"},
-    {file = "coverage-5.2.1-cp36-cp36m-win_amd64.whl", hash = "sha256:b1ed2bdb27b4c9fc87058a1cb751c4df8752002143ed393899edb82b131e0546"},
-    {file = "coverage-5.2.1-cp37-cp37m-macosx_10_13_x86_64.whl", hash = "sha256:c890728a93fffd0407d7d37c1e6083ff3f9f211c83b4316fae3778417eab9811"},
-    {file = "coverage-5.2.1-cp37-cp37m-manylinux1_i686.whl", hash = "sha256:538f2fd5eb64366f37c97fdb3077d665fa946d2b6d95447622292f38407f9258"},
-    {file = "coverage-5.2.1-cp37-cp37m-manylinux1_x86_64.whl", hash = "sha256:27ca5a2bc04d68f0776f2cdcb8bbd508bbe430a7bf9c02315cd05fb1d86d0034"},
-    {file = "coverage-5.2.1-cp37-cp37m-win32.whl", hash = "sha256:aab75d99f3f2874733946a7648ce87a50019eb90baef931698f96b76b6769a46"},
-    {file = "coverage-5.2.1-cp37-cp37m-win_amd64.whl", hash = "sha256:c2ff24df02a125b7b346c4c9078c8936da06964cc2d276292c357d64378158f8"},
-    {file = "coverage-5.2.1-cp38-cp38-macosx_10_9_x86_64.whl", hash = "sha256:304fbe451698373dc6653772c72c5d5e883a4aadaf20343592a7abb2e643dae0"},
-    {file = "coverage-5.2.1-cp38-cp38-manylinux1_i686.whl", hash = "sha256:c96472b8ca5dc135fb0aa62f79b033f02aa434fb03a8b190600a5ae4102df1fd"},
-    {file = "coverage-5.2.1-cp38-cp38-manylinux1_x86_64.whl", hash = "sha256:8505e614c983834239f865da2dd336dcf9d72776b951d5dfa5ac36b987726e1b"},
-    {file = "coverage-5.2.1-cp38-cp38-win32.whl", hash = "sha256:700997b77cfab016533b3e7dbc03b71d33ee4df1d79f2463a318ca0263fc29dd"},
-    {file = "coverage-5.2.1-cp38-cp38-win_amd64.whl", hash = "sha256:46794c815e56f1431c66d81943fa90721bb858375fb36e5903697d5eef88627d"},
-    {file = "coverage-5.2.1-cp39-cp39-macosx_10_13_x86_64.whl", hash = "sha256:16042dc7f8e632e0dcd5206a5095ebd18cb1d005f4c89694f7f8aafd96dd43a3"},
-    {file = "coverage-5.2.1-cp39-cp39-manylinux1_i686.whl", hash = "sha256:c1bbb628ed5192124889b51204de27c575b3ffc05a5a91307e7640eff1d48da4"},
-    {file = "coverage-5.2.1-cp39-cp39-manylinux1_x86_64.whl", hash = "sha256:4f6428b55d2916a69f8d6453e48a505c07b2245653b0aa9f0dee38785939f5e4"},
-    {file = "coverage-5.2.1-cp39-cp39-win32.whl", hash = "sha256:9e536783a5acee79a9b308be97d3952b662748c4037b6a24cbb339dc7ed8eb89"},
-    {file = "coverage-5.2.1-cp39-cp39-win_amd64.whl", hash = "sha256:b8f58c7db64d8f27078cbf2a4391af6aa4e4767cc08b37555c4ae064b8558d9b"},
-    {file = "coverage-5.2.1.tar.gz", hash = "sha256:a34cb28e0747ea15e82d13e14de606747e9e484fb28d63c999483f5d5188e89b"},
 ]
 distlib = [
     {file = "distlib-0.3.1-py2.py3-none-any.whl", hash = "sha256:8c09de2c67b3e7deef7184574fc060ab8a793e7adbb183d942c389c8b13c52fb"},
@@ -643,10 +369,6 @@ filelock = [
     {file = "filelock-3.0.12-py3-none-any.whl", hash = "sha256:929b7d63ec5b7d6b71b0fa5ac14e030b3f70b75747cef1b10da9b879fef15836"},
     {file = "filelock-3.0.12.tar.gz", hash = "sha256:18d82244ee114f543149c66a6e0c14e9c4f8a1044b5cdaadd0f82159d6a6ff59"},
 ]
-funcsigs = [
-    {file = "funcsigs-1.0.2-py2.py3-none-any.whl", hash = "sha256:330cc27ccbf7f1e992e69fef78261dc7c6569012cf397db8d3de0234e6c937ca"},
-    {file = "funcsigs-1.0.2.tar.gz", hash = "sha256:a7bb0f2cf3a3fd1ab2732cb49eba4252c2af4240442415b4abce3b87022a8f50"},
-]
 importlib-metadata = [
     {file = "importlib_metadata-0.23-py2.py3-none-any.whl", hash = "sha256:d5f18a79777f3aa179c145737780282e27b508fc8fd688cb17c7a813e8bd39af"},
     {file = "importlib_metadata-0.23.tar.gz", hash = "sha256:aa18d7378b00b40847790e7c27e11673d7fed219354109d0e7b9e5b25dc3ad26"},
@@ -654,21 +376,14 @@ importlib-metadata = [
 importlib-resources = [
     {file = "importlib_resources-1.0.2-py2.py3-none-any.whl", hash = "sha256:6e2783b2538bd5a14678284a3962b0660c715e5a0f10243fd5e00a4b5974f50b"},
     {file = "importlib_resources-1.0.2.tar.gz", hash = "sha256:d3279fd0f6f847cced9f7acc19bd3e5df54d34f93a2e7bb5f238f81545787078"},
-    {file = "importlib_resources-3.0.0-py2.py3-none-any.whl", hash = "sha256:d028f66b66c0d5732dae86ba4276999855e162a749c92620a38c1d779ed138a7"},
-    {file = "importlib_resources-3.0.0.tar.gz", hash = "sha256:19f745a6eca188b490b1428c8d1d4a0d2368759f32370ea8fb89cad2ab1106c3"},
 ]
 more-itertools = [
-    {file = "more-itertools-5.0.0.tar.gz", hash = "sha256:38a936c0a6d98a38bcc2d03fdaaedaba9f412879461dd2ceff8d37564d6522e4"},
-    {file = "more_itertools-5.0.0-py2-none-any.whl", hash = "sha256:c0a5785b1109a6bd7fac76d6837fd1feca158e54e521ccd2ae8bfe393cc9d4fc"},
-    {file = "more_itertools-5.0.0-py3-none-any.whl", hash = "sha256:fe7a7cae1ccb57d33952113ff4fa1bc5f879963600ed74918f1236e212ee50b9"},
     {file = "more-itertools-7.2.0.tar.gz", hash = "sha256:409cd48d4db7052af495b09dec721011634af3753ae1ef92d2b32f73a745f832"},
     {file = "more_itertools-7.2.0-py3-none-any.whl", hash = "sha256:92b8c4b06dac4f0611c0729b2f2ede52b2e1bac1ab48f089c7ddc12e26bb60c4"},
-    {file = "more-itertools-8.4.0.tar.gz", hash = "sha256:68c70cc7167bdf5c7c9d8f6954a7837089c6a36bf565383919bb595efb8a17e5"},
-    {file = "more_itertools-8.4.0-py3-none-any.whl", hash = "sha256:b78134b2063dd214000685165d81c154522c3ee0a1c0d4d113c80361c234c5a2"},
 ]
 packaging = [
-    {file = "packaging-20.4-py2.py3-none-any.whl", hash = "sha256:998416ba6962ae7fbd6596850b80e17859a5753ba17c32284f67bfff33784181"},
-    {file = "packaging-20.4.tar.gz", hash = "sha256:4357f74f47b9c12db93624a82154e9b120fa8293699949152b22065d556079f8"},
+    {file = "packaging-20.9-py2.py3-none-any.whl", hash = "sha256:67714da7f7bc052e064859c05c595155bd1ee9f69f76557e21f051443c20947a"},
+    {file = "packaging-20.9.tar.gz", hash = "sha256:5b327ac1320dc863dca72f4514ecc086f31186744b84a230374cc1fd776feae5"},
 ]
 pathlib2 = [
     {file = "pathlib2-2.3.5-py2.py3-none-any.whl", hash = "sha256:0ec8205a157c80d7acc301c0b18fbd5d44fe655968f5d947b6ecef5290fc35db"},
@@ -679,8 +394,8 @@ pluggy = [
     {file = "pluggy-0.13.1.tar.gz", hash = "sha256:15b2acde666561e1298d71b523007ed7364de07029219b604cf808bfa1c765b0"},
 ]
 py = [
-    {file = "py-1.9.0-py2.py3-none-any.whl", hash = "sha256:366389d1db726cd2fcfc79732e75410e5fe4d31db13692115529d34069a043c2"},
-    {file = "py-1.9.0.tar.gz", hash = "sha256:9ca6883ce56b4e8da7e79ac18787889fa5206c79dcc67fb065376cd2fe03f342"},
+    {file = "py-1.10.0-py2.py3-none-any.whl", hash = "sha256:3b80836aa6d1feeaa108e046da6423ab8f6ceda6468545ae8d02d9d58d18818a"},
+    {file = "py-1.10.0.tar.gz", hash = "sha256:21b81bda15b66ef5e1a777a21c4dcd9c20ad3efd0b3f817e7a809035269e1bd3"},
 ]
 pyparsing = [
     {file = "pyparsing-2.4.7-py2.py3-none-any.whl", hash = "sha256:ef9d7589ef3c200abe66653d3f1ab1033c3c419ae9b9bdb1240a85b024efc88b"},
@@ -707,17 +422,13 @@ scandir = [
     {file = "scandir-1.10.0-cp37-cp37m-win_amd64.whl", hash = "sha256:b24086f2375c4a094a6b51e78b4cf7ca16c721dcee2eddd7aa6494b42d6d519d"},
     {file = "scandir-1.10.0.tar.gz", hash = "sha256:4d4631f6062e658e9007ab3149a9b914f3548cb38bfb021c64f39a025ce578ae"},
 ]
-singledispatch = [
-    {file = "singledispatch-3.4.0.3-py2.py3-none-any.whl", hash = "sha256:833b46966687b3de7f438c761ac475213e53b306740f1abfaa86e1d1aae56aa8"},
-    {file = "singledispatch-3.4.0.3.tar.gz", hash = "sha256:5b06af87df13818d14f08a028e42f566640aef80805c3b50c5056b086e3c2b9c"},
-]
 six = [
     {file = "six-1.15.0-py2.py3-none-any.whl", hash = "sha256:8b74bedcbbbaca38ff6d7491d76f2b06b3592611af620f8426e82dddb04a5ced"},
     {file = "six-1.15.0.tar.gz", hash = "sha256:30639c035cdb23534cd4aa2dd52c3bf48f06e5f4a941509c8bafd8ce11080259"},
 ]
 toml = [
-    {file = "toml-0.10.1-py2.py3-none-any.whl", hash = "sha256:bda89d5935c2eac546d648028b9901107a595863cb36bae0c73ac804a9b4ce88"},
-    {file = "toml-0.10.1.tar.gz", hash = "sha256:926b612be1e5ce0634a2ca03470f95169cf16f939018233a670519cb4ac58b0f"},
+    {file = "toml-0.10.2-py2.py3-none-any.whl", hash = "sha256:806143ae5bfb6a3c6e736a764057db0e6a0e05e338b5630894a5f779cabb4f9b"},
+    {file = "toml-0.10.2.tar.gz", hash = "sha256:b3bda1d108d5dd99f4a20d24d9c348e91c4db7ab1b749200bded2f839ccbe68f"},
 ]
 tox = [
     {file = "tox-3.14.0-py2.py3-none-any.whl", hash = "sha256:0bc216b6a2e6afe764476b4a07edf2c1dab99ed82bb146a1130b2e828f5bff5e"},
@@ -728,8 +439,8 @@ typing = [
     {file = "typing-3.7.4.3.tar.gz", hash = "sha256:1187fb9c82fd670d10aa07bbb6cfcfe4bdda42d6fab8d5134f04e8c4d0b71cc9"},
 ]
 virtualenv = [
-    {file = "virtualenv-20.0.31-py2.py3-none-any.whl", hash = "sha256:e0305af10299a7fb0d69393d8f04cb2965dda9351140d11ac8db4e5e3970451b"},
-    {file = "virtualenv-20.0.31.tar.gz", hash = "sha256:43add625c53c596d38f971a465553f6318decc39d98512bc100fa1b1e839c8dc"},
+    {file = "virtualenv-20.4.3-py2.py3-none-any.whl", hash = "sha256:83f95875d382c7abafe06bd2a4cdd1b363e1bb77e02f155ebe8ac082a916b37c"},
+    {file = "virtualenv-20.4.3.tar.gz", hash = "sha256:49ec4eb4c224c6f7dd81bb6d0a28a09ecae5894f4e593c89b0db0885f565a107"},
 ]
 wcwidth = [
     {file = "wcwidth-0.2.5-py2.py3-none-any.whl", hash = "sha256:beb4802a9cebb9144e99086eff703a642a13d6a0052920003a230f3294bbe784"},
diff --git a/pyproject.toml b/pyproject.toml
index ec703fa..ab2b468 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,7 @@
 [tool]
 [tool.poetry]
 name = "expandvars"
-version = "0.6.5"  # Also update expandvars.py
+version = "0.7.0"  # Also update expandvars.py
 description = "Expand system variables Unix style"
 license = "MIT"
 keywords = ["expand", "system", "variables"]
@@ -29,12 +29,12 @@ authors = ["Arijit Basu <sayanarijit@gmail.com>"]
 readme = "README.md"
 
 [tool.poetry.dependencies]
-python = "*"
+python = ">=3.4"
 
 [tool.poetry.dev-dependencies]
-tox = ">=3.7.0"
-pytest = {version = ">=4.6.1", optional = true}
-pytest-cov = {version = ">=2.7.1", optional = true}
+tox = "*"
+pytest = "*"
+pytest-cov = "*"
 
 [tool.poetry.extras]
 testing = ["pytest", "pytest-cov"]
diff --git a/tox.ini b/tox.ini
index d3c82f2..698e23c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py27,py34,py35,py36,py37
+envlist = py34,py35,py36,py37
 
 [testenv]
 whitelist_externals =