code: public static <T extends Number> WithinGroup<T> percentileCont(T arg) {
          if (arg.doubleValue() < 0.0 || arg.doubleValue() > 1.0) {
              throw new IllegalArgumentException("The percentile value should be a number between 0 and 1");
          }
          return percentileCont(ConstantImpl.create(arg));
      }
docs: Calculates a percentile based on a continuous distribution of the column value
  
  @param arg argument
  @return percentile_cont(arg)