code: func (ng *Engine) NewRangeQuery(q storage.Queryable, qs string, start, end time.Time, interval time.Duration) (Query, error) {
  	expr, err := ParseExpr(qs)
  	if err != nil {
  		return nil, err
  	}
  	if expr.Type() != ValueTypeVector && expr.Type() != ValueTypeScalar {
  		return nil, errors.Errorf("invalid expression type %q for range query, must be Scalar or instant Vector", documentedType(expr.Type()))
  	}
  	qry := ng.newQuery(q, expr, start, end, interval)
  	qry.q = qs
  
  	return qry, nil
  }
docs: // NewRangeQuery returns an evaluation query for the given time range and with
  // the resolution set by the interval.