code: function max$3(comparer) {
      var max = (typeof comparer === 'function')
          ? function (x, y) { return comparer(x, y) > 0 ? x : y; }
          : function (x, y) { return x > y ? x : y; };
      return this.lift(new reduce_1.ReduceOperator(max));
  }
docs: The Max operator operates on an Observable that emits numbers (or items that can be evaluated as numbers),
  and when source Observable completes it emits a single item: the item with the largest number.
  
  <img src="./img/max.png" width="100%">
  
  @param {Function} optional comparer function that it will use instead of its default to compare the value of two
  items.
  @return {Observable} an Observable that emits item with the largest number.
  @method max
  @owner Observable