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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 get_ins_off(self, off):
 """ Get a particular instruction by using the address :param off: address of the instruction :type off: int :rtype: an :class:`Instruction` object """

        idx = 0
        for i in self.get_instructions():
            if idx == off:
                return i
            idx += i.get_length()
        return None