Move contents of builtins/* to stdlib/*. This simplifies finding stubs.

stdlib/3/itertools.pyi

@@ -0,0 +1,57 @@
+# Stubs for itertools
+
+# Based on http://docs.python.org/3.2/library/itertools.html
+
+from typing import (Iterator, TypeVar, Iterable, overload, Any, Callable, Tuple,
+                    Union, Sequence)
+
+_T = TypeVar('_T')
+_S = TypeVar('_S')
+
+def count(start: int = ...,
+          step: int = ...) -> Iterator[int]: ... # more general types?
+def cycle(iterable: Iterable[_T]) -> Iterator[_T]: ...
+
+@overload
+def repeat(object: _T) -> Iterator[_T]: ...
+@overload
+def repeat(object: _T, times: int) -> Iterator[_T]: ...
+
+def accumulate(iterable: Iterable[_T]) -> Iterator[_T]: ...
+def chain(*iterables: Iterable[_T]) -> Iterator[_T]: ...
+# TODO chain.from_Iterable
+def compress(data: Iterable[_T], selectors: Iterable[Any]) -> Iterator[_T]: ...
+def dropwhile(predicate: Callable[[_T], Any],
+              iterable: Iterable[_T]) -> Iterator[_T]: ...
+def filterfalse(predicate: Callable[[_T], Any],
+                iterable: Iterable[_T]) -> Iterator[_T]: ...
+
+@overload
+def groupby(iterable: Iterable[_T]) -> Iterator[Tuple[_T, Iterator[_T]]]: ...
+@overload
+def groupby(iterable: Iterable[_T],
+            key: Callable[[_T], _S]) -> Iterator[Tuple[_S, Iterator[_T]]]: ...
+
+@overload
+def islice(iterable: Iterable[_T], stop: int) -> Iterator[_T]: ...
+@overload
+def islice(iterable: Iterable[_T], start: int, stop: int,
+           step: int = ...) -> Iterator[_T]: ...
+
+def starmap(func: Any, iterable: Iterable[Any]) -> Iterator[Any]: ...
+def takewhile(predicate: Callable[[_T], Any],
+              iterable: Iterable[_T]) -> Iterator[_T]: ...
+def tee(iterable: Iterable[Any], n: int = ...) -> Iterator[Any]: ...
+def zip_longest(*p: Iterable[Any],
+                fillvalue: Any = ...) -> Iterator[Any]: ...
+
+# TODO: Return type should be Iterator[Tuple[..]], but unknown tuple shape.
+#       Iterator[Sequence[_T]] loses this type information.
+def product(*p: Iterable[_T], repeat: int = ...) -> Iterator[Sequence[_T]]: ...
+
+def permutations(iterable: Iterable[_T],
+                 r: Union[int, None] = ...) -> Iterator[Sequence[_T]]: ...
+def combinations(iterable: Iterable[_T],
+                 r: int) -> Iterable[Sequence[_T]]: ...
+def combinations_with_replacement(iterable: Iterable[_T],
+                                  r: int) -> Iterable[Sequence[_T]]: ...