docs: function (methodName) {
        for (var _len = arguments.length, args = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
          args[_key - 1] = arguments[_key];
        }
  
        var ret = emberA();
  
        this.forEach(function (x, idx) {
          var method = x && x[methodName];
  
          if ('function' === typeof method) {
            ret[idx] = args ? method.apply(x, args) : x[methodName]();
          }
        }, this);
  
        return ret;
      }