ok   bounty ids are exactly 0..495
  ok   claim ids are exactly 0..721
  ok   every claim points at a real bounty
  ok   ClaimCreated.bountyIssuer matches BountyCreated.issuer
  ok   ClaimCreated.createdAt is a plausible unix time
  ok   ClaimCreated's 7th word repeats the claim id
  ok   accepted and cancelled never overlap
  ok   accepted + cancelled + open == 496  278+169+49
  ok   every ClaimAccepted fee == amount*25/1000 exactly
  ok   ClaimAccepted.bountyIssuer matches BountyCreated.issuer
  ok   ClaimAccepted.claimIssuer matches that claim's ClaimCreated issuer
  ok   the accepted claim belongs to the accepted bounty
  ok   BountyCancelled.issuer matches BountyCreated.issuer
  ok   722 mints, 0 burns
  ok   one mint per claim id
  ok   every NFT is minted to the contract itself (escrow)
  ok   mint happens in the same tx as its ClaimCreated
  ok   exactly one NFT released per accepted bounty  278 vs 278
  ok   each released NFT is the accepted claim, sent to the bounty issuer
  ok   contract ETH balance == sum of open bounty amounts  218195711000000000 vs 218195711000000000
  ok   gross == net-to-claimers + fees
  ok   funded == paid + refunded + still-open

  funded total         6.536511134 ETH over 496 bounties
  paid out (gross)     3.726923002 ETH over 278 completed
    -> to claimers     3.633749927 ETH
    -> to treasury     0.093173075 ETH  (0x1a706a29822921d6c641e472bd33cf945a13fef9)
  refunded (cancelled) 2.591392421 ETH over 169 bounties
  still escrowed       0.218195711 ETH over 49 open

all invariants hold