data to look up
the function used to compare iterators in the sequence
user data passed to iter_cmp
an glib.SequenceIter pointing to the position of the first item found equal to data according to iter_cmp and cmp_data, or NULL if no such item exists
2.28
Like Sequence.lookup, but uses a GSequenceIterCompareFunc instead of a GCompareDataFunc as the compare function.
iter_cmp is called with two iterators pointing into seq. It should return 0 if the iterators are equal, a negative value if the first iterator comes before the second, and a positive value if the second iterator comes before the first.
This function will fail if the data contained in the sequence is unsorted.