docs: def visit_reference(self, node: docutils.nodes.reference) -> None:
          """Called for "reference" nodes."""
          # if len(node.children) != 1 or not isinstance(node.children[0], docutils.nodes.Text) \
          #         or not all(_ in node.attributes for _ in ('name', 'refuri')):
          #     return
          path = pathlib.Path(node.attributes['refuri'])
          try:
              if path.is_absolute():
                  return
              resolved_path = path.resolve()
          except FileNotFoundError:  # in resolve(), prior to Python 3.6
              return
          # except OSError:  # in is_absolute() and resolve(), on URLs in Windows
          #     return
          try:
              resolved_path.relative_to(HERE)
          except ValueError:
              return
          if not path.is_file():
              return
          assert node.attributes['name'] == node.children[0].astext()
          self.references.append(node)