Moves the data pointed to by @iter to a new position as indicated by
@cmp_func. This
function should be called for items in a sequence already sorted according
to @cmp_func whenever some aspect of an item changes so that @cmp_func
may return different values for that item.
@cmp_func is called with two items of the @seq, and @cmp_data.
It should return 0 if the items are equal, a negative value if
the first item comes before the second, and a positive value if
the second item comes before the first.
Moves the data pointed to by @iter to a new position as indicated by @cmp_func. This function should be called for items in a sequence already sorted according to @cmp_func whenever some aspect of an item changes so that @cmp_func may return different values for that item.
@cmp_func is called with two items of the @seq, and @cmp_data. It should return 0 if the items are equal, a negative value if the first item comes before the second, and a positive value if the second item comes before the first.