code: func (idx *Index) BatchQuery(queries ...PQLQuery) *PQLBatchQuery {
  	stringQueries := make([]string, 0, len(queries))
  	hasKeys := false
  	for _, query := range queries {
  		serializedQuery := query.Serialize()
  		hasKeys = hasKeys || serializedQuery.HasWriteKeys()
  		stringQueries = append(stringQueries, serializedQuery.String())
  	}
  	return &PQLBatchQuery{
  		index:   idx,
  		queries: stringQueries,
  		hasKeys: hasKeys,
  	}
  }
docs: // BatchQuery creates a batch query with the given queries.