code: public static Expression adjusthue(Generator generator, FunctionCall input) {
          Color color = input.getExpectedColorParam(0);
          int changeInDegrees = input.getExpectedIntParam(1);
          Color.HSL hsl = color.getHSL();
          hsl.setH(hsl.getH() + changeInDegrees);
          return hsl.getColor();
      }
docs: Adjusts the hue of the given color by the given number of degrees.
  
  @param generator the surrounding generator
  @param input     the function call to evaluate
  @return the result of the evaluation