def GetScriptHashesForVerifying(self):
        """
        Get a list of script hashes for verifying transactions.

        Raises:
            Exception: if there are no valid transactions to claim from.

        Returns:
            list: of UInt160 type script hashes.
        """
        hashes = super(ClaimTransaction, self).GetScriptHashesForVerifying()

        for hash, group in groupby(self.Claims, lambda x: x.PrevHash):
            tx, height = Blockchain.Default().GetTransaction(hash)

            if tx is None:
                raise Exception("Invalid Claim Operation")

            for claim in group:
                if len(tx.outputs) <= claim.PrevIndex:
                    raise Exception("Invalid Claim Operation")

                script_hash = tx.outputs[claim.PrevIndex].ScriptHash

                if script_hash not in hashes:
                    hashes.append(script_hash)

        hashes.sort()

        return hashes
Get a list of script hashes for verifying transactions.

        Raises:
            Exception: if there are no valid transactions to claim from.

        Returns:
            list: of UInt160 type script hashes.