anchor.diff:  
   /// A helper class holds params of link context.
   /// Footnote creation needs other info in [_tryCreateReferenceLink].
  -class LinkContext {
  +class _LinkContext {
     final InlineParser parser;
     final SimpleDelimiter opener;
     final List<Node> Function() getChildren;
   
  -  const LinkContext(this.parser, this.opener, this.getChildren);
  +  const _LinkContext(this.parser, this.opener, this.getChildren);
   }
   
   /// Matches links like `[blah][label]` and `[blah](url)`.
  
positive.code:     String? tag,
      required List<Node> Function() getChildren,
    }) {
      final context = LinkContext(parser, opener, getChildren);
      final text = parser.source.substring(opener.endPos, parser.pos);
      // The current character is the `]` that closed the link text. Examine the
      // next character, to determine what type of link we might have (a '('
  
negative.code:   ///
    /// Returns the nodes if it was successfully created, `null` otherwise.
    Iterable<Node>? _tryCreateReferenceLink(
      _LinkContext context,
      String label,
    ) {
      final parser = context.parser;
  