code: func (q *PQLBatchQuery) Add(query PQLQuery) {
  	err := query.Error()
  	if err != nil {
  		q.err = err
  	}
  	serializedQuery := query.Serialize()
  	q.hasKeys = q.hasKeys || serializedQuery.HasWriteKeys()
  	q.queries = append(q.queries, serializedQuery.String())
  }
docs: // Add adds a query to the batch.