Transform an old-style comparison function to a key function. Used with tools that accept key functions (such as sorted(), min(), max(), heapq.nlargest(), heapq.nsmallest(), itertools.groupby()). This function is primarily used as a transition tool for programs being converted from Python 2 which supported the use of comparison functions.
functools.cmp_to_key(func)sorted(iterable, key=cmp_to_key(locale.strcoll)) locale-aware sort order