Returns the name of a sprite map The name is derived from the folder than
    contains the sprites.

def _sprite_map_name(map):
    """
    Returns the name of a sprite map The name is derived from the folder than
    contains the sprites.
    """
    map = StringValue(map).value
    sprite_map = sprite_maps.get(map)
    if not sprite_map:
        log.error("No sprite map found: %s", map)
    if sprite_map:
        return StringValue(sprite_map['*n*'])
    return StringValue(None)