Revert "One possible implementation of models"

This reverts commit 7519ef0.

src/tdastro/__init__.py

@@ -1 +1,3 @@
-from .base_models import PhysicalModel
+from .example_module import greetings, meaning
+
+__all__ = ["greetings", "meaning"]

src/tdastro/example_module.py

@@ -0,0 +1,23 @@
+"""An example module containing simplistic functions."""
+
+
+def greetings() -> str:
+    """A friendly greeting for a future friend.
+
+    Returns
+    -------
+    str
+        A typical greeting from a software engineer.
+    """
+    return "Hello from LINCC-Frameworks!"
+
+
+def meaning() -> int:
+    """The meaning of life, the universe, and everything.
+
+    Returns
+    -------
+    int
+        The meaning of life.
+    """
+    return 42

tests/tdastro/test_example_module.py

@@ -0,0 +1,13 @@
+from tdastro import example_module
+
+
+def test_greetings() -> None:
+    """Verify the output of the `greetings` function"""
+    output = example_module.greetings()
+    assert output == "Hello from LINCC-Frameworks!"
+
+
+def test_meaning() -> None:
+    """Verify the output of the `meaning` function"""
+    output = example_module.meaning()
+    assert output == 42