protected function default_atts() {

		$atts = array();

		if ( ! $this->hasConfigKey( 'atts' ) ) {
			return $atts;
		}

		$atts_config = $this->getConfigKey( 'atts' );
		array_walk( $atts_config,
			function ( $att_properties, $att_label ) use ( &$atts ) {
				$atts[ $att_label ] = $att_properties['default'];
			}
		);

		return $atts;
	}