code: public static <A extends Number & Comparable<?>> NumberExpression<Integer> sign(Expression<A> num) {
          return Expressions.numberOperation(Integer.class, Ops.MathOps.SIGN, num);
      }
docs: Create a {@code sign(num)} expression
  
  <p>Returns the positive (+1), zero (0), or negative (-1) sign of num.</p>
  
  @param num numeric expression
  @return sign(num)