Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/@python2/popen2.pyi

@@ -0,0 +1,27 @@
+from typing import Any, Iterable, List, Optional, TextIO, Tuple, TypeVar, Union
+
+_T = TypeVar("_T")
+
+class Popen3:
+    sts: int
+    cmd: Iterable[Any]
+    pid: int
+    tochild: TextIO
+    fromchild: TextIO
+    childerr: Optional[TextIO]
+    def __init__(self, cmd: Iterable[Any] = ..., capturestderr: bool = ..., bufsize: int = ...) -> None: ...
+    def __del__(self) -> None: ...
+    def poll(self, _deadstate: _T = ...) -> Union[int, _T]: ...
+    def wait(self) -> int: ...
+
+class Popen4(Popen3):
+    childerr: None
+    cmd: Iterable[Any]
+    pid: int
+    tochild: TextIO
+    fromchild: TextIO
+    def __init__(self, cmd: Iterable[Any] = ..., bufsize: int = ...) -> None: ...
+
+def popen2(cmd: Iterable[Any] = ..., bufsize: int = ..., mode: str = ...) -> Tuple[TextIO, TextIO]: ...
+def popen3(cmd: Iterable[Any] = ..., bufsize: int = ..., mode: str = ...) -> Tuple[TextIO, TextIO, TextIO]: ...
+def popen4(cmd: Iterable[Any] = ..., bufsize: int = ..., mode: str = ...) -> Tuple[TextIO, TextIO]: ...