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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 draw(self, name, dname, draw_branches=True):
 """ Writes the current graph as a PNG file :param str name: filename (without .png) :param str dname: directory of the output png :param draw_branches: :return: """

        from pydot import Dot, Edge
        import os

        g = Dot()
        g.set_node_defaults(color='lightgray',
                            style='filled',
                            shape='box',
                            fontname='Courier',
                            fontsize='10')
        for node in sorted(self.nodes, key=lambda x: x.num):
            if draw_branches and node.type.is_cond:
                g.add_edge(Edge(str(node), str(node.true), color='green'))
                g.add_edge(Edge(str(node), str(node.false), color='red'))
            else:
                for suc in self.sucs(node):
                    g.add_edge(Edge(str(node), str(suc), color='blue'))
            for except_node in self.catch_edges.get(node, []):
                g.add_edge(Edge(str(node),
                                str(except_node),
                                color='black',
                                style='dashed'))

        g.write(os.path.join(dname, '%s.png' % name), format='png')