// Check validity of _block as a transaction. To do this we just deserialise and attempt to determine the sender. If it doesn't work, the signature is bad.
// Check validity of _transactionRLP as a transaction. To do this we just deserialise and attempt to determine the sender.
// If it doesn't work, the signature is bad.
// The transaction's nonce may yet be invalid (or, it could be "valid" but we may be missing a marginally older transaction).
// The transaction's nonce may yet be invalid (or, it could be "valid" but we may be missing a marginally older transaction).