Improve several stubs. (math, _random, time, etc.)

Some of these are derived from mypy/stubs/.

2.7/cStringIO.pyi

@@ -1,43 +1,39 @@
-"""Stub file for the 'cStringIO' module."""
-# This is an autogenerated file. It serves as a starting point
-# for a more precise manual annotation of this module.
-# Feel free to edit the source below, but remove this header when you do.
+# Stubs for cStringIO (Python 2.7)
+# See https://docs.python.org/2/library/stringio.html
 
-from typing import Any, List, Tuple, Dict, GenericType
+from typing import IO, List, Iterable, Iterator, Any, Union
 
-InputType = ...  # type: StringI
-OutputType = ...  # type: StringO
-cStringIO_CAPI = ...  # type: object
+class StringIO(IO[str]):
+    softspace = ... # type: int
 
-def StringIO(*args, **kwargs) -> Any: ...
-
-
-class StringI(object):
-    def close() -> None: ...
-    def flush() -> None: ...
-    def getvalue(*args, **kwargs) -> str: ...
-    def isatty() -> bool: ...
-    def read(*args, **kwargs) -> str: ...
-    def readline(*args, **kwargs) -> str: ...
-    def readlines(*args, **kwargs) -> List[str]: ...
-    def reset() -> None: ...
-    def seek(a: int, *args, **kwargs) -> None: ...
-    def tell() -> int: ...
-    def truncate(*args, **kwargs) -> None:
+    def __init__(self, s: str = None) -> None: ...
+    def getvalue(self) -> str: ...
+    def close(self) -> None: ...
+    @property
+    def closed(self) -> bool: ...
+    def fileno(self) -> int: ...
+    def flush(self) -> None: ...
+    def isatty(self) -> bool: ...
+    def read(self, size: int = -1) -> str: ...
+    def readable(self) -> bool: ...
+    def readline(self, size: int = -1) -> str: ...
+    def readlines(self, hint: int = -1) -> List[str]: ...
+    def seek(self, offset: int, whence: int = ...) -> None: ...
+    def seekable(self) -> bool: ...
+    def tell(self) -> int: ...
+    def truncate(self, size: int = None) -> int:
         raise IOError()
-
-class StringO(object):
-    def close() -> None: ...
-    def flush() -> None: ...
-    def getvalue(*args, **kwargs) -> str: ...
-    def isatty() -> bool: ...
-    def read(*args, **kwargs) -> str: ...
-    def readline(*args, **kwargs) -> str: ...
-    def readlines(*args, **kwargs) -> List[str]: ...
+    def writable(self) -> bool: ...
+    def writelines(self, lines: Iterable[str]) -> None: ...
+    def next(self) -> str: ...
+    def __iter__(self) -> StringI: ...
+    def __enter__(self) -> Any: ...
+    def __exit__(self, exc_type: type, exc_val: Any, exc_tb: Any) -> Any: ...
+    # only StringO:
     def reset() -> None: ...
-    def seek(a: int, *args, **kwargs) -> None: ...
-    def tell() -> int: ...
-    def truncate(*args, **kwargs) -> None:
-        raise IOError()
-    def write(a) -> None: ...
-    def writelines(*args, **kwargs) -> None: ...
+    def write(self, b: Union[str, unicode]) -> None: ...
+    def writelines(self, lines: Iterable[Union[str, unicode]]) -> None: ...
+
+InputType = StringIO
+OutputType = StringIO
+