How to use the zen-observable/extras.merge.apply function in zen-observable

var subReducer = fn(obj);
        // there are two forms of return the subreducer can have
        // straight stream form
        // or object form where we need to scan it into string
        if (subReducer.source && subReducer.reducer) {
          // object form
          subReducer = scan(subReducer.source, subReducer.reducer || function (_, n) {
            return n;
          }, _this.initialState[k]);
        }
        return subReducer.map(function (x) {
          return _defineProperty({}, k, x);
        }); // map to its particular namespace
      });
      var source = merge.apply(undefined, _toConsumableArray(sources));
      var reducer = function reducer(acc, n) {
        return _extends({}, acc, n);
      };
      return { source: source, reducer: reducer };
    }
  }]);