code: function max(input, expression) {
      if(!isArray(input)) {
          return input;
      }
      return isUndefined(expression)
          ? Math.max.apply(Math, input)
          : input[indexByMath('max', input, expression)]
  }
docs: @name max
  @kind function
  
  @description
  Math.max will get an array return the max value. if an expression
  is provided, will return max value by expression.