orm.go
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
}
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
}
// Between creates a between query.