<｜begin▁of▁sentence｜>### Instruction:
How would you override the default draw method of an igraph Graph to implement custom drawing behavior and output the result to a PNG file using cairo, assuming you have a graph with edges and vertices already added?
### Response:
import igraph as ig
import cairo

class GraphArtist(ig.Graph):
    def draw(self, *args, **kwds):
        print('Custom draw method called')
        super(GraphArtist, self).draw(*args, **kwds)

# Example usage creating a GraphArtist object and drawing it to a PNG file
# Assuming edges and vertices have been added to 'my_graph'
my_graph = GraphArtist()

# Draw the graph to a PNG file
surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, 400, 400)
context = cairo.Context(surface)
my_graph.draw(context)
surface.write_to_png('output.png')
<|EOT|>
