code: def get_asset_id(cls, transactions):
          
  
          if not isinstance(transactions, list):
              transactions = [transactions]
  
          # create a set of the transactions' asset ids
          asset_ids = {tx.id if tx.operation == tx.CREATE
                       else tx.asset['id']
                       for tx in transactions}
  
          # check that all the transasctions have the same asset id
          if len(asset_ids) > 1:
              raise AssetIdMismatch(('All inputs of all transactions passed'
                                     ' need to have the same asset id'))
          return asset_ids.pop()
docs: Get the asset id from a list of :class:`~.Transactions`.
  
          This is useful when we want to check if the multiple inputs of a
          transaction are related to the same asset id.
  
          Args:
              transactions (:obj:`list` of :class:`~bigchaindb.common.
                  transaction.Transaction`): A list of Transactions.
                  Usually input Transactions that should have a matching
                  asset ID.
  
          Returns:
              str: ID of the asset.
  
          Raises:
              :exc:`AssetIdMismatch`: If the inputs are related to different
                  assets.