binary-search-tree/red-black-tree

import assert from 'assert';

import Node from '../types/Node.js';

/**
 * Computes the grandparent (parent of parent) of the input node.
 *
 * @param {Node} node - The input node.
 * @returns {Node}
 */
const grandparent = (node) => {
    assert(node instanceof Node);
    // We only call this function when node HAS a grandparent
    assert(node.parent !== null);
    assert(node.parent.parent !== null);
    return node.parent.parent;
};

export default grandparent;