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

    def expand_route(route):
        if isinstance(route, (Mapping, list, tuple)):
            return MapRoute(route)
        if isinstance(route, string_t):
            return mlazy(expand_router_string, route)
        return route
    if (routes is None):
        return ()
    if (not isinstance(routes, (list, tuple))):
        routes = (routes,)
    return [expand_route(route) for route in routes]

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

def prepare(routes):