code: func (s *SelectStatement) RewriteTimeFields() {
  	for i := 0; i < len(s.Fields); i++ {
  		switch expr := s.Fields[i].Expr.(type) {
  		case *VarRef:
  			if expr.Val == "time" {
  				s.TimeAlias = s.Fields[i].Alias
  				s.Fields = append(s.Fields[:i], s.Fields[i+1:]...)
  			}
  		}
  	}
  }
docs: // RewriteTimeFields removes any "time" field references.