fetches the entry point for a plugin and calls it with the given
    aux_info

def load_plugin(category, name, aux_info=None):
    '''fetches the entry point for a plugin and calls it with the given
    aux_info'''
    func = load_simple_endpoint(category, name)
    if aux_info is None:
        return func()
    else:
        return func(aux_info)
    raise KeyError(name)