I used the following method to remove duplicate items in a list and got confused by the error.
>>> a [[1, 2], [1, 2], [2, 3]] >>> noDups=[ u for u in a if u not in locals()['_[1]'] ] Traceback (most recent call last): File "<interactive input>", line 1, in ? TypeError: iterable argument required -- http://mail.python.org/mailman/listinfo/python-list