Generates name for variant images based settings (by variants sizes).

def get_variant_label(v_conf):
    """
    Generates name for variant images based settings (by variants sizes).
    """
    if v_conf['MAX_SIZE'][0] is None:
        return 'h{}'.format(v_conf['MAX_SIZE'][1])
    if v_conf['MAX_SIZE'][1] is None:
        return 'w{}'.format(v_conf['MAX_SIZE'][0])
    return '{}x{}'.format(*v_conf['MAX_SIZE'])