public void Define( AST.StructOrUnion structOrUnion, ImmutableList<Tuple<Option<String>, ExprType>> members) { var _members = members.ConvertAll(_ => Tuple.Create(_.Item1.Value, _.Item2)); if (structOrUnion == AST.StructOrUnion.STRUCT) { DefineStruct(_members); } else { DefineUnion(_members); } }