human
Here's a good function header given the following:
I wrote the below code

    N = len(sequence)
    def f(i):
        (div, mod) = divmod(i, N)
        if ((div % 2) == 0):
            return sequence[mod]
        else:
            return sequence[((N - mod) - 1)]
    return partial(_force, sequence=_advance(f))

What's a good function header?
assistant
#Here's a good function header.

def bounce(sequence):