docs: function walk(data, path, result, key) {
      var fn;
  
      switch (type(path)) {
        case 'string':
          fn = seekSingle;
          break;
  
        case 'array':
          fn = seekArray;
          break;
  
        case 'object':
          fn = seekObject;
          break;
      }
  
      if (fn) {
        fn(data, path, result, key);
      }
    }