if (leftNode.canMerge(rightNode)) { return mergeNodes(leftNode, rightNode);
if (leftNode.canMerge(rightNode)) { return mergeNodes(leftNode, rightNode);
if (leftNode.canMerge(rightNode)) { return mergeNodes(leftNode, rightNode);
if (leftNode.canMerge(rightNode)) { return mergeNodes(leftNode, rightNode);