Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/wsgiref/validate.pyi

@@ -0,0 +1,52 @@
+import sys
+from _typeshed.wsgi import ErrorStream, InputStream, WSGIApplication
+from typing import Any, Callable, Iterable, Iterator, NoReturn, Optional
+
+class WSGIWarning(Warning): ...
+
+def validator(application: WSGIApplication) -> WSGIApplication: ...
+
+class InputWrapper:
+    input: InputStream
+    def __init__(self, wsgi_input: InputStream) -> None: ...
+    if sys.version_info < (3,):
+        def read(self, size: int = ...) -> bytes: ...
+        def readline(self) -> bytes: ...
+    else:
+        def read(self, size: int) -> bytes: ...
+        def readline(self, size: int = ...) -> bytes: ...
+    def readlines(self, hint: int = ...) -> bytes: ...
+    def __iter__(self) -> Iterable[bytes]: ...
+    def close(self) -> NoReturn: ...
+
+class ErrorWrapper:
+    errors: ErrorStream
+    def __init__(self, wsgi_errors: ErrorStream) -> None: ...
+    def write(self, s: str) -> None: ...
+    def flush(self) -> None: ...
+    def writelines(self, seq: Iterable[str]) -> None: ...
+    def close(self) -> NoReturn: ...
+
+class WriteWrapper:
+    writer: Callable[[bytes], Any]
+    def __init__(self, wsgi_writer: Callable[[bytes], Any]) -> None: ...
+    def __call__(self, s: bytes) -> None: ...
+
+class PartialIteratorWrapper:
+    iterator: Iterator[bytes]
+    def __init__(self, wsgi_iterator: Iterator[bytes]) -> None: ...
+    def __iter__(self) -> IteratorWrapper: ...
+
+class IteratorWrapper:
+    original_iterator: Iterator[bytes]
+    iterator: Iterator[bytes]
+    closed: bool
+    check_start_response: Optional[bool]
+    def __init__(self, wsgi_iterator: Iterator[bytes], check_start_response: Optional[bool]) -> None: ...
+    def __iter__(self) -> IteratorWrapper: ...
+    if sys.version_info < (3,):
+        def next(self) -> bytes: ...
+    else:
+        def __next__(self) -> bytes: ...
+    def close(self) -> None: ...
+    def __del__(self) -> None: ...