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

    @empty_if_none
    def transform_function(key):
        path = key.to_path()
        path_index = (index * 2)
        return unicode(path[path_index])
    return transform_function

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

def key_kind_n(index):