cmp_func is passed two items of
seq and should
return 0 if they are equal, a negative value if the
first comes before the second, and a positive value
if the second comes before the first.
Available since: 2.14
This method is not directly available to language bindings.
The function used to sort the sequence.
User data passed to
The argument can be
The data is owned by the caller of the method.