'close() -> None or (perhaps) an integer.  Close the file.
Sets data attribute .closed to True.  A closed file cannot be used for
further I/O operations.  close() may be called more than once without
error.  Some kinds of file objects (for example, opened by popen())
may return an exit status upon closing.'

def close(self):

    self.iterator = None
    self.closed = True
