added stub file for popen2 (#1385)

Author: pkordas

stdlib/2/popen2.pyi

@@ -0,0 +1,29 @@
+from typing import Any, Iterable, List, Optional, Union, TextIO, Tuple, TypeVar
+
+_T = TypeVar('_T')
+
+__all__ = ...  # type: List[str]
+
+class Popen3:
+    sts = ...  # type: int
+    cmd = ...  # type: Iterable
+    pid = ...  # type: int
+    tochild = ...  # type: TextIO
+    fromchild = ...  # type: TextIO
+    childerr = ...  # type: Optional[TextIO]
+    def __init__(self, cmd: Iterable = ..., 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 = ...  # type: None
+    cmd = ...  # type: Iterable
+    pid = ...  # type: int
+    tochild = ...  # type: TextIO
+    fromchild = ...  # type: TextIO
+    def __init__(self, cmd: Iterable = ..., bufsize: int = ...) -> None: ...
+
+def popen2(cmd: Iterable = ..., bufsize: int = ..., mode: str = ...) -> Tuple[TextIO, TextIO]: ...
+def popen3(cmd: Iterable = ..., bufsize: int = ..., mode: str = ...) -> Tuple[TextIO, TextIO, TextIO]: ...
+def popen4(cmd: Iterable = ..., bufsize: int = ..., mode: str = ...) -> Tuple[TextIO, TextIO]: ...