private static function get_field( $target_id = 0, $field = '' ) {
		if ( self::is_active() ) {
			if ( $field ) {
				return self::get_single_field( $target_id, $field );
			} else {
				return self::get_all_fields( $target_id );
			}
		}
		return $field ? null : [];
	}