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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 _op(self, line, op=None, offset=0):
 """ Returns the gate name for placing a gate on a line. :param int line: Line number. :param int op: Operation number or, by default, uses the current op count. :return: Gate name. :rtype: string """

        if op is None:
            op = self.op_count[line]
        return "line{}_gate{}".format(line, op + offset)