public function _subtabs() {
		$subtabs = $this->version >= 2 && method_exists( $this, 'subtabs' ) ? $this->subtabs() : false;

		foreach ( $this->_tabs() as $tab_id => $tab_label ) {
			if ( empty( $subtabs[ $tab_id ] ) || ! is_array( $subtabs[ $tab_id ] ) ) {
				$subtabs[ $tab_id ] = array(
					'main' => $tab_label,
				);
			}
		}

		return apply_filters( 'pum_shortcode_subtabs', $subtabs, $this->tag() );
	}