* equivalent to regular Java division, {@code p / q}; and if it is {@link RoundingMode#FLOOR},
   * then this method is equivalent to {@link Math#floorDiv(int,int) Math.floorDiv}{@code (p, q)}.
   *
   * @throws ArithmeticException if {@code q == 0}, or if {@code mode == UNNECESSARY} and {@code a}
   *     is not an integer multiple of {@code b}
   */

   * equivalent to regular Java division, {@code p / q}; and if it is {@link RoundingMode#FLOOR},
   * then this method is equivalent to {@link Math#floorDiv(long,long) Math.floorDiv}{@code (p, q)}.
   *
   * @throws ArithmeticException if {@code q == 0}, or if {@code mode == UNNECESSARY} and {@code a}
   *     is not an integer multiple of {@code b}
   */
  @GwtIncompatible // TODO

          // Check the assertions we make in the javadoc.
          if (mode == DOWN) {
            assertEquals(p / q, LongMath.divide(p, q, mode));
          } else if (mode == FLOOR) {
            assertEquals(Math.floorDiv(p, q), LongMath.divide(p, q, mode));
          }
        }
      }
    }
  }

  @GwtIncompatible // TODO
  @AndroidIncompatible // Bug in older versions of Android we test against, since fixed.