private bool MaybeAlreadyError <T>(NamedList <T> members, INamed named) where T : class, INamedMember { if (members.ContainsKey(named)) { var already = members[named].Name; Errors.AtToken(ErrNo.Syntax001, named.Name, $"``{named.Name}´´ defined here ..."); Errors.AtToken(ErrNo.Syntax002, already, $"... is already defined here"); return(true); } return(false); }