def popitem(self):
        for key in self.iterkeys():
            return (key, self.pop(key))     # This is only run once.
        else:
            raise KeyError('No messages in mailbox')
Delete an arbitrary (key, message) pair and return it.
dataset/ETHPy150Open babble/babble/include/jython/Lib/mailbox.py/Mailbox.popitem