    def _remove_signatures(tx_dict):
        """Takes a Transaction dictionary and removes all signatures.

            Args:
                tx_dict (dict): The Transaction to remove all signatures from.

            Returns:
                dict

        """
        # NOTE: We remove the reference since we need `tx_dict` only for the
        #       transaction's hash
        tx_dict = deepcopy(tx_dict)
        for input_ in tx_dict['inputs']:
            # NOTE: Not all Cryptoconditions return a `signature` key (e.g.
            #       ThresholdSha256), so setting it to `None` in any
            #       case could yield incorrect signatures. This is why we only
            #       set it to `None` if it's set in the dict.
            input_['fulfillment'] = None
        return tx_dict
Takes a Transaction dictionary and removes all signatures.

Args:
tx_dict (dict): The Transaction to remove all signatures from.

Returns:
dict
bigchaindb/common/transaction.py