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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 dbg_draw(self, filename):
 """ Draw the graph and save it to a PNG file. """

        import matplotlib.pyplot as pyplot  # pylint: disable=import-error
        from networkx.drawing.nx_agraph import graphviz_layout  # pylint: disable=import-error

        tmp_graph = networkx.DiGraph()
        for from_block, to_block in self.transition_graph.edges():
            node_a = "%#08x" % from_block.addr
            node_b = "%#08x" % to_block.addr
            if node_b in self._ret_sites:
                node_b += "[Ret]"
            if node_a in self._call_sites:
                node_a += "[Call]"
            tmp_graph.add_edge(node_a, node_b)
        pos = graphviz_layout(tmp_graph, prog='fdp')   # pylint: disable=no-member
        networkx.draw(tmp_graph, pos, node_size=1200)
        pyplot.savefig(filename)