code: public static RuntimeException codeBug(String msg)
          throws RuntimeException
      {
          msg = "FAILED ASSERTION: " + msg;
          RuntimeException ex = new IllegalStateException(msg);
          // Print stack trace ASAP
          ex.printStackTrace(System.err);
          throw ex;
      }
docs: Throws RuntimeException to indicate failed assertion.
  The function never returns and its return type is RuntimeException
  only to be able to write <tt>throw Kit.codeBug()</tt> if plain
  <tt>Kit.codeBug()</tt> triggers unreachable code error.