Fun transformation problem

[Jonathan Wright]

def trans(paths):
tree = {}
for path in paths:
branch = tree
for i,node in enumerate(path[:-2]):
branch = branch.setdefault(node, {})
branch[path[-2]] = path[-1]
return tree

print trans( [(1,2,3), (1,3,4), (2,5,6)] )
print trans( [(1,2,3,4), (3,4,5,6), (3,4,6,7), (3,4,6,8), (3,4,5,1),
(3,4,7,9)] )

This is my first post with gmail. The preview shows it screwing up the
spaces in the python code, so I'm includeding a version with dots
instead of spaces below. :-)

def trans(paths):
....tree = {}
....for path in paths:
........branch = tree
........for i,node in enumerate(path[:-2]):
............branch = branch.setdefault(node, {})
........branch[path[-2]] = path[-1]
....return tree

Jonathan.