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

    def expand_route(route):
        if isinstance(route, dict):
            return MapRoute(route)
        if isinstance(route, basestring):
            return mpromise(instantiate, route)
        return route
    if (routes is None):
        return ()
    if (not isinstance(routes, (list, tuple))):
        routes = (routes,)
    return map(expand_route, routes)

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

def prepare(routes):