Return hash reverting for and calculate count of reverted txns
        :return: root_hash, for reverting to (needed in revertToHead method) and count of reverted txns

def reject_batch(self):
        """
        Return hash reverting for and calculate count of reverted txns
        :return: root_hash, for reverting to (needed in revertToHead method) and count of reverted txns
        """
        prev_size = 0
        if len(self.un_committed) == 0:
            raise LogicError("No items to return")
        if len(self.un_committed) > 0:
            _, _, prev_size = self.un_committed.pop()
        if len(self.un_committed) == 0:
            committed_hash, committed_root, committed_size = self.last_committed
            return committed_hash, committed_root, prev_size - committed_size
        else:
            lhash, ltxn_root, lsize = self.un_committed[-1]
            return lhash, ltxn_root, prev_size - lsize