[Question] Combinator to necessarily match delimiter between parser matches about superpower HOT 1 CLOSED

var doc = Doc.AtEnd().Parse(tokens);

        private static readonly TokenListParser<TokenKind, string> If =
            from _ in Token.EqualTo(TokenKind.If)
            from id in Identifier
            from nl1 in OptionalNewLines
            from lbracket in Token.EqualTo(TokenKind.LBracket)
            from nl2 in OptionalNewLines
            from lines in Identifier.Try().ManyDelimitedBy(NewLine.AtLeastOnce())
            from nl3 in OptionalNewLines
            from rbracket in Token.EqualTo(TokenKind.RBracket)
            from trailing in OptionalNewLines // <------------------------- Added
            select "(" + id + "): { " + String.Join(", ", lines) + " }";

        private static readonly TokenListParser<TokenKind, string> Doc =
            from nl1 in OptionalNewLines
            from ifs in If.Many()
            select String.Join(" | ", ifs);