code: public static WindowOver<Double> regrCount(Expression<? extends Number> arg1, Expression<? extends Number> arg2) {
          return new WindowOver<Double>(Double.class, SQLOps.REGR_COUNT, arg1, arg2);
      }
docs: REGR_COUNT returns an integer that is the number of non-null number pairs used to fit the regression line.
  
  @param arg1 first arg
  @param arg2 second arg
  @return regr_count(arg1, arg2)