'Render graphviz dot graph'

def render(self, fp, name, annotate_defs=False):

    fp.write(('digraph    %s    {\n' % name))
    fp.write('    node    [shape=box];\n')
    for child in self.children:
        child.render(fp, self, annotate_defs)
    fp.write('}\n')
