fileinput.input函数 是对 fileinput.FileInput 类的再封装
def input(files=None, inplace=False, backup="", bufsize=0,
mode="r", openhook=None):
"""Return an instance of the FileInput class, which can be iterated.
The parameters are passed to the constructor of the FileInput class.
The returned instance, in addition to being an iterator,
keeps global state for the functions of this module,.
"""
global _state
if _state and _state._file:
raise RuntimeError("input() already active")
_state = FileInput(files, inplace, backup, bufsize, mode, openhook)
return _state
fileinput.input函数 是对 fileinput.FileInput 类的再封装
fileinput.FileInput 类是对 open 函数的再封窗