A GSequenceIterCompareFunc is a function used to compare iterators.
It must return zero if the iterators compare equal, a negative value
if a comes before b, and a positive value if b comes before a.
aliasGSequenceIterCompareFunc = intfunction(GSequenceIter* a, GSequenceIter* b, void* data)
A GSequenceIterCompareFunc is a function used to compare iterators. It must return zero if the iterators compare equal, a negative value if a comes before b, and a positive value if b comes before a.