A simpler API:
def flatten(sequence, atomic_test = lambda o: isinstance(o,basestring)): """ don't recurse into iterables if atomic_test -> True """
Yes, this is also the API I would have suggested. Simple, but flexible enough to handle the odd cases with the occasional user-defined iterable non-containers.
STeVe -- http://mail.python.org/mailman/listinfo/python-list
