code: public T fps(Object rangeStart, Object rangeEnd){
          if (rangeEnd == null && rangeStart == null){
              throw new IllegalArgumentException("At least one of [rangeStart, rangeEnd] must be provided");
          }
          StringBuilder builder = new StringBuilder();
          if (rangeStart != null){
              builder.append(rangeStart);
          }
  
          builder.append("-");
  
          if (rangeEnd != null){
              builder.append(rangeEnd);
          }
  
          return param("fps", builder.toString());
      }
docs: fps (frames per second) parameter for video
  @param rangeStart String or Number, can be null for open range.
  @param rangeEnd String or Number, can be null for open range.
  @return the transformation for chaining.