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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def lock(self, lock=True, changelist=0):
 """Locks or unlocks the file :param lock: Lock or unlock the file :type lock: bool :param changelist: Optional changelist to checkout the file into :type changelist: :class:`.Changelist` """


        cmd = 'lock' if lock else 'unlock'
        if changelist:
            self._connection.run([cmd, '-c', changelist, self.depotFile])
        else:
            self._connection.run([cmd, self.depotFile])

        self.query()