code: private static double submissionRate(final ZonedDateTime a, final ZonedDateTime b) {
          return SUBMISSION_RATE_DIVIDEND / (a.toInstant().toEpochMilli() - b.toInstant().toEpochMilli());
      }
docs: Computes the instantaneous rate in between two given dates corresponding to two submissions.
  
  @param a First date.
  @param b Second date.
  @return Instantaneous submission rate in submissions/sec, e.g. {@code a - b}.