Re-organize directory structure (#4971)

See discussion in #2491

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

stdlib/@python2/re.pyi

@@ -0,0 +1,108 @@
+from typing import (
+    Any,
+    AnyStr,
+    Callable,
+    Dict,
+    Generic,
+    Iterator,
+    List,
+    Match,
+    Optional,
+    Pattern,
+    Sequence,
+    Tuple,
+    Union,
+    overload,
+)
+
+# ----- re variables and constants -----
+DEBUG: int
+I: int
+IGNORECASE: int
+L: int
+LOCALE: int
+M: int
+MULTILINE: int
+S: int
+DOTALL: int
+X: int
+VERBOSE: int
+U: int
+UNICODE: int
+T: int
+TEMPLATE: int
+
+class error(Exception): ...
+
+@overload
+def compile(pattern: AnyStr, flags: int = ...) -> Pattern[AnyStr]: ...
+@overload
+def compile(pattern: Pattern[AnyStr], flags: int = ...) -> Pattern[AnyStr]: ...
+@overload
+def search(pattern: Union[str, unicode], string: AnyStr, flags: int = ...) -> Optional[Match[AnyStr]]: ...
+@overload
+def search(pattern: Union[Pattern[str], Pattern[unicode]], string: AnyStr, flags: int = ...) -> Optional[Match[AnyStr]]: ...
+@overload
+def match(pattern: Union[str, unicode], string: AnyStr, flags: int = ...) -> Optional[Match[AnyStr]]: ...
+@overload
+def match(pattern: Union[Pattern[str], Pattern[unicode]], string: AnyStr, flags: int = ...) -> Optional[Match[AnyStr]]: ...
+@overload
+def split(pattern: Union[str, unicode], string: AnyStr, maxsplit: int = ..., flags: int = ...) -> List[AnyStr]: ...
+@overload
+def split(
+    pattern: Union[Pattern[str], Pattern[unicode]], string: AnyStr, maxsplit: int = ..., flags: int = ...
+) -> List[AnyStr]: ...
+@overload
+def findall(pattern: Union[str, unicode], string: AnyStr, flags: int = ...) -> List[Any]: ...
+@overload
+def findall(pattern: Union[Pattern[str], Pattern[unicode]], string: AnyStr, flags: int = ...) -> List[Any]: ...
+
+# Return an iterator yielding match objects over all non-overlapping matches
+# for the RE pattern in string. The string is scanned left-to-right, and
+# matches are returned in the order found. Empty matches are included in the
+# result unless they touch the beginning of another match.
+@overload
+def finditer(pattern: Union[str, unicode], string: AnyStr, flags: int = ...) -> Iterator[Match[AnyStr]]: ...
+@overload
+def finditer(pattern: Union[Pattern[str], Pattern[unicode]], string: AnyStr, flags: int = ...) -> Iterator[Match[AnyStr]]: ...
+@overload
+def sub(pattern: Union[str, unicode], repl: AnyStr, string: AnyStr, count: int = ..., flags: int = ...) -> AnyStr: ...
+@overload
+def sub(
+    pattern: Union[str, unicode], repl: Callable[[Match[AnyStr]], AnyStr], string: AnyStr, count: int = ..., flags: int = ...
+) -> AnyStr: ...
+@overload
+def sub(
+    pattern: Union[Pattern[str], Pattern[unicode]], repl: AnyStr, string: AnyStr, count: int = ..., flags: int = ...
+) -> AnyStr: ...
+@overload
+def sub(
+    pattern: Union[Pattern[str], Pattern[unicode]],
+    repl: Callable[[Match[AnyStr]], AnyStr],
+    string: AnyStr,
+    count: int = ...,
+    flags: int = ...,
+) -> AnyStr: ...
+@overload
+def subn(
+    pattern: Union[str, unicode], repl: AnyStr, string: AnyStr, count: int = ..., flags: int = ...
+) -> Tuple[AnyStr, int]: ...
+@overload
+def subn(
+    pattern: Union[str, unicode], repl: Callable[[Match[AnyStr]], AnyStr], string: AnyStr, count: int = ..., flags: int = ...
+) -> Tuple[AnyStr, int]: ...
+@overload
+def subn(
+    pattern: Union[Pattern[str], Pattern[unicode]], repl: AnyStr, string: AnyStr, count: int = ..., flags: int = ...
+) -> Tuple[AnyStr, int]: ...
+@overload
+def subn(
+    pattern: Union[Pattern[str], Pattern[unicode]],
+    repl: Callable[[Match[AnyStr]], AnyStr],
+    string: AnyStr,
+    count: int = ...,
+    flags: int = ...,
+) -> Tuple[AnyStr, int]: ...
+def escape(string: AnyStr) -> AnyStr: ...
+def purge() -> None: ...
+def template(pattern: Union[AnyStr, Pattern[AnyStr]], flags: int = ...) -> Pattern[AnyStr]: ...