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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 definitions(self):
 """ Get all definitions located at the current instruction address. :return: A list of ProgramVariable instances. :rtype: list """


        defs = set()

        if self._simplified:
            graph = self._ddg.simplified_data_graph
        else:
            graph = self._ddg.data_graph

        for n in graph.nodes():  # type: ProgramVariable
            if n.location.ins_addr == self._insn_addr:
                defs.add(DDGViewItem(self._ddg, n, simplified=self._simplified))

        return list(defs)