Type Iterator.from

lib/core.js

@@ -1753,6 +1753,16 @@ interface $Iterable<+Yield,+Return,-Next> {
 }
 type Iterable<+T> = $Iterable<T,void,void>;
 
+interface IteratorConstructor {
+    /**
+     * This method allows wrapping "iterator-like" objects with an iterator.
+     * @returns The argument object if it's already an iterator, or a wrapping iterator if the passed object implements a callable @@iterator property.
+     */
+    from<+Yield,+Return,-Next>(source: $Iterable<Yield,Return,Next>): $Iterator<Yield,Return,Next>;
+ }
+
+declare var Iterator: IteratorConstructor;
+
 interface Generator<+Yield,+Return,-Next> {
     @@iterator(): $Iterator<Yield,Return,Next>;
     next(value?: Next): IteratorResult<Yield,Return>;

tests/iterator_helpers/.flowconfig

@@ -0,0 +1,3 @@
+[options]
+no_flowlib=false
+all=true

tests/iterator_helpers/from.js

@@ -0,0 +1,2 @@
+/* @flow */
+(Iterator.from([1]): Iterator<number>);

tests/iterator_helpers/iterator_helpers.exp

@@ -0,0 +1 @@
+Found 0 errors