Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/timeit.pyi

@@ -0,0 +1,42 @@
+import sys
+from typing import IO, Any, Callable, Dict, List, Optional, Sequence, Text, Tuple, Union
+
+_str = Union[str, Text]
+_Timer = Callable[[], float]
+_stmt = Union[_str, Callable[[], Any]]
+
+default_timer: _Timer
+
+class Timer:
+    if sys.version_info >= (3, 5):
+        def __init__(
+            self, stmt: _stmt = ..., setup: _stmt = ..., timer: _Timer = ..., globals: Optional[Dict[str, Any]] = ...
+        ) -> None: ...
+    else:
+        def __init__(self, stmt: _stmt = ..., setup: _stmt = ..., timer: _Timer = ...) -> None: ...
+    def print_exc(self, file: Optional[IO[str]] = ...) -> None: ...
+    def timeit(self, number: int = ...) -> float: ...
+    def repeat(self, repeat: int = ..., number: int = ...) -> List[float]: ...
+    if sys.version_info >= (3, 6):
+        def autorange(self, callback: Optional[Callable[[int, float], Any]] = ...) -> Tuple[int, float]: ...
+
+if sys.version_info >= (3, 5):
+    def timeit(
+        stmt: _stmt = ..., setup: _stmt = ..., timer: _Timer = ..., number: int = ..., globals: Optional[Dict[str, Any]] = ...
+    ) -> float: ...
+    def repeat(
+        stmt: _stmt = ...,
+        setup: _stmt = ...,
+        timer: _Timer = ...,
+        repeat: int = ...,
+        number: int = ...,
+        globals: Optional[Dict[str, Any]] = ...,
+    ) -> List[float]: ...
+
+else:
+    def timeit(stmt: _stmt = ..., setup: _stmt = ..., timer: _Timer = ..., number: int = ...) -> float: ...
+    def repeat(
+        stmt: _stmt = ..., setup: _stmt = ..., timer: _Timer = ..., repeat: int = ..., number: int = ...
+    ) -> List[float]: ...
+
+def main(args: Optional[Sequence[str]]) -> None: ...