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

    def fading(gf, t):
        gft = gf(t)
        if np.isscalar(t):
            factor = min(((1.0 * (clip.duration - t)) / duration), 1)
            factor = np.array([factor, factor])
        else:
            factor = np.minimum(((1.0 * (clip.duration - t)) / duration), 1)
            factor = np.vstack([factor, factor]).T
        return (factor * gft)
    return clip.fl(fading, keep_duration=True)

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

@audio_video_fx
@requires_duration
def audio_fadeout(clip, duration):