While using some nested data structures, I've seen that I'd like to have a function that tells me if a given data structure contains one or more cyclic references (a way to recognise a cycle in a graph is to do a depth-first search, marking vertices along the way. An already marked vertex means a cycle.) Do you know where I can find a function like this?
http://python.org/doc/current/lib/module-pprint.html#l2h-749 -- http://mail.python.org/mailman/listinfo/python-list
