docs: function (node, key) {
    'use strict';
    var i, k;
  
    if (node.key === key) {
      return node;
    } else {
      for (i = 0; i < node.children.length; i += 1) {
        k = slow_findKey(node.children[i], key);
        if (k) {
          return k;
        }
      }
    }
  }