[Python] shortcut?

[Rob Hudson]

Is there a Python shortcut for the following?

if d.has_key(k):
	d[k].append(v)
else:
	d[k] = [v]

I'm keeping a dictionary of key:list pairs and I'm writing the above 
often.  I think I remember seeing a shortcut to something like this but 
I can't recall what it was.

Thanks,
Rob