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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 kill_definitions(self, atom, code_loc, data=None, dummy=True):
 """ Overwrite existing definitions w.r.t 'atom' with a dummy definition instance. A dummy definition will not be removed during simplification. :param Atom atom: :param CodeLocation code_loc: :param object data: :return: None """


        if data is None:
            data = DataSet(Undefined(atom.size), atom.size)

        self.kill_and_add_definition(atom, code_loc, data, dummy=dummy)