code: def make_link_node(rawtext, app, type, slug, options):
      
  
      try:
          base = app.config.github_project_url
          if not base:
              raise AttributeError
          if not base.endswith('/'):
              base += '/'
      except AttributeError as err:
          raise ValueError('github_project_url configuration value is not set (%s)' % str(err))
  
      ref = base + type + '/' + slug + '/'
      set_classes(options)
      prefix = "#"
      if type == 'pull':
          prefix = "PR " + prefix
      node = nodes.reference(rawtext, prefix + utils.unescape(slug), refuri=ref,
                             **options)
      return node
docs: Create a link to a github resource.
  
      :param rawtext: Text being replaced with link node.
      :param app: Sphinx application context
      :param type: Link type (issues, changeset, etc.)
      :param slug: ID of the thing to link to
      :param options: Options dictionary passed to role func.