code: public static <T1 extends Comparable<T1>, T2 extends Comparable<T2>, T3 extends Comparable<T3>> int compare(T1 a1, T1 b1, T2 a2, T2 b2, T3 a3, T3 b3) {
          int res = 0;
  
          if ((res = N.compare(a1, b1)) != 0) {
              return res;
          } else if ((res = N.compare(a2, b2)) != 0) {
              return res;
          }
  
          return N.compare(a3, b3);
      }
docs: Continue to compare the pairs of values <code>(a1, b1), (a2, b2), (a3, b3)</code> until they're not equal.
  <code>0</code> is returned if all of the pairs of values are equal.
  
  @param a1
  @param b1
  @param a2
  @param b2
  @param a3
  @param b3
  @return