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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 add_ref(self, ref):
 """ Add a reference to a memory data object. :param CodeReference ref: The reference. :return: None """


        self.refs[ref.insn_addr].append(ref)
        self.data_addr_to_ref[ref.memory_data.addr].append(ref)