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

    def gen_candidates():
        (yield os.path.join(six.moves.getcwd(), u'matplotlibrc'))
        try:
            matplotlibrc = os.environ[u'MATPLOTLIBRC']
        except KeyError:
            pass
        else:
            (yield matplotlibrc)
            (yield os.path.join(matplotlibrc, u'matplotlibrc'))
        (yield os.path.join(_get_configdir(), u'matplotlibrc'))
        (yield os.path.join(get_data_path(), u'matplotlibrc'))
    for fname in gen_candidates():
        if os.path.isfile(fname):
            break
    return fname

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

def matplotlib_fname():