functools.py

"""Skeleton for 'functools' stdlib module."""


def reduce(function, sequence, initial=None):
    """Apply a function of two arguments cumulatively to the items of a
    sequence, from left to right, so as to reduce the sequence to a single
    value.

    :type function: collections.Callable
    :type sequence: collections.Iterable
    :type initial: T
    :rtype: T | unknown
    """
    return initial