def add_child(graph, child_id, child_label, parent_id, colour):
node = pydot.Node(child_id, style="<STR_LIT>", fillcolor=colour, label=child_label, shape="<STR_LIT>", fontname=FONT)<EOL>graph.add_node(node)<EOL>graph.add_edge(pydot.Edge(parent_id, node))<EOL>
http://www.graphviz.org/doc/info/shapes.html#polygon