const HALVING_INCREMENT: u32 = SUBSIDY_HALVING_INTERVAL % DIFFCHANGE_INTERVAL;

    // For valid degrees the relationship between epoch_offset and period_offset
    // will increment by 336 every halving.
    let relationship = period_offset + SUBSIDY_HALVING_INTERVAL * CYCLE_EPOCHS - epoch_offset;

    if relationship % HALVING_INCREMENT != 0 {
      bail!("relationship between epoch offset and period offset must be multiple of 336");
    }

    let epochs_since_cycle_start = relationship % DIFFCHANGE_INTERVAL / HALVING_INCREMENT;

    let epoch = cycle_start_epoch + epochs_since_cycle_start;

    let height = Height(epoch * SUBSIDY_HALVING_INTERVAL + epoch_offset);

    let (block_offset, rest) = match rest.split_once('‴') {
      Some((block_offset, rest)) => (block_offset.parse::<u64>()?, rest),
      None => (0, rest),
    };

    if !rest.is_empty() {
      bail!("trailing characters");
    }

    if block_offset >= height.subsidy() {
      bail!("invalid block offset");
    }

    Ok(height.starting_sat() + block_offset)