  function _getTier(uint8 _tier, uint8 _numberOfTiers) internal view returns (Tier memory) {
    Tier memory tier = _tiers[_tier];
    uint16 _lastClosedDrawId = lastClosedDrawId;
    if (tier.drawId != _lastClosedDrawId) {
      tier.drawId = _lastClosedDrawId;
      tier.prizeSize = uint96(
        _computePrizeSize(
          _tier,
          _numberOfTiers,
          fromUD34x4toUD60x18(tier.prizeTokenPerShare),
          fromUD34x4toUD60x18(prizeTokenPerShare)
        )
      );
    }
    return tier;
  }
