private PunctuationSyntax XmlMakeBeginCommentToken(SyntaxList<SyntaxNode> precedingTrivia, Func<SyntaxList<SyntaxNode>> scanTrailingTrivia)
{
Debug.Assert(PeekChar() == '<');
Debug.Assert(PeekAheadChar(1) == '!');
Debug.Assert(PeekAheadChar(2) == '-');
Debug.Assert(PeekAheadChar(3) == '-');
AdvanceChar(4);
var followingTrivia = scanTrailingTrivia();
return MakePunctuationToken(SyntaxKind.LessThanExclamationMinusMinusToken, "<!--", precedingTrivia, followingTrivia);
}