- isRevoked(stateID: uint, commitment: commitment, revocationWitness: bytes) -> bool
 - assert self.openingClaimsInProgress[hash(state.parameters.openingCommitments)]
    ... .redeemedCoins == 0`
    - if any of the opening state has been redeemed, all state must now be redeemed.
 - assert validateCommitment(...) for each commitment in the revocation witness
 - assert from revocationWitness.closureApprovals that each of
   state.parameters.participants signed off on hash(closureCommitments)