code: func GetMulticastGroup(db sqlx.Queryer, id uuid.UUID, forUpdate bool) (MulticastGroup, error) {
  	var mg MulticastGroup
  	var fu string
  
  	if forUpdate {
  		fu = " for update"
  	}
  
  	err := sqlx.Get(db, &mg, `
  		select
  			*
  		from
  			multicast_group
  		where
  			id = $1`+fu,
  		id,
  	)
  	if err != nil {
  		return mg, handlePSQLError(err, "select error")
  	}
  	return mg, nil
  }
docs: // GetMulticastGroup returns the multicast-group for the given ID.