qrcode.chapril.org/vendor/wikimedia/less.php/lib/Less/VisitorReplacing.php

<?php
/**
 * @private
 */
class Less_VisitorReplacing extends Less_Visitor {

	public function visitObj( $node ) {
		$funcName = 'visit' . $node->type;
		if ( isset( $this->_visitFnCache[$funcName] ) ) {

			$visitDeeper = true;
			$node = $this->$funcName( $node, $visitDeeper );

			if ( $node ) {
				if ( $visitDeeper && is_object( $node ) ) {
					$node->accept( $this );
				}

				$funcName .= "Out";
				if ( isset( $this->_visitFnCache[$funcName] ) ) {
					$this->$funcName( $node );
				}
			}

		} else {
			$node->accept( $this );
		}

		return $node;
	}

	public function visitArray( $nodes ) {
		$newNodes = [];
		foreach ( $nodes as $node ) {
			$evald = $this->visitObj( $node );
			if ( $evald ) {
				if ( is_array( $evald ) ) {
					self::flatten( $evald, $newNodes );
				} else {
					$newNodes[] = $evald;
				}
			}
		}
		return $newNodes;
	}

	public function flatten( $arr, &$out ) {
		foreach ( $arr as $item ) {
			if ( !is_array( $item ) ) {
				$out[] = $item;
				continue;
			}

			foreach ( $item as $nestedItem ) {
				if ( is_array( $nestedItem ) ) {
					self::flatten( $nestedItem, $out );
				} else {
					$out[] = $nestedItem;
				}
			}
		}

		return $out;
	}

}