docs: def build_kwargs(self):
          """ Construct the kwargs to pass to batch_get_item """
          keys, self.keys = self.keys[:MAX_GET_BATCH], self.keys[MAX_GET_BATCH:]
          query = {'ConsistentRead': self.consistent}
          if self.attributes is not None:
              query['ProjectionExpression'] = self.attributes
          if self.alias:
              query['ExpressionAttributeNames'] = self.alias
          query['Keys'] = keys
          return {
              'RequestItems': {
                  self.tablename: query,
              },
              'ReturnConsumedCapacity': self.return_capacity,
          }