code: func (idx *Index) Count(row *PQLRowQuery) *PQLBaseQuery {
  	serializedQuery := row.serialize()
  	q := NewPQLBaseQuery(fmt.Sprintf("Count(%s)", serializedQuery.String()), idx, nil)
  	q.hasKeys = q.hasKeys || serializedQuery.HasWriteKeys()
  	return q
  }
docs: // Count creates a Count query.
  // Returns the number of set columns in the ROW_CALL passed in.