odds and ends

how to define repr method on transactions before Tx.hash is defined?
define Block.__repr__
define a ConsensusError and raise it whenever violations encountered

scenarios

there needs to be at least 1 transaction -- the coinbase
bad coinbase outpoint
coinbase amount
good coinbase
spend non-existant amount
sum of ouputs exceed sum of inputs
bad p2pk sig
good p2pk tx (spend to p2pkh)
bad merkle root
p2pkh public key doesn't have right hashgood p2pk tx
p2pkh public key hashes correctly, sig is bad
good p2pkh tx
(advanced) how would we support reorgs?

commentary

perhaps it would be better to define the BitcoinNode or Blockchain class near the beginning and unittest the consesus failures as we go. this is a little more organized and helps explain the significance of new concepts, but it ruins the "simulation" idea ...