code: def open(self, file, mode='r', buffering=-1, encoding=None,
               errors=None, newline=None, closefd=True, opener=None):
          
          if opener is not None and sys.version_info < (3, 3):
              raise TypeError(
                  "open() got an unexpected keyword argument 'opener'")
          fake_open = FakeFileOpen(self.filesystem, use_io=True)
          return fake_open(file, mode, buffering, encoding, errors,
                           newline, closefd, opener)
docs: Redirect the call to FakeFileOpen.
          See FakeFileOpen.call() for description.