code: func (f *Field) Between(a int, b int) *PQLRowQuery {
  	text := fmt.Sprintf("Range(%s >< [%d,%d])", f.name, a, b)
  	q := NewPQLRowQuery(text, f.index, nil)
  	q.hasKeys = f.options.keys || f.index.options.keys
  	return q
  }
docs: // Between creates a between query.