code: def get_links(self, request=None):
          
          links = LinkNode()
  
          # Generate (path, method, view) given (path, method, callback).
          paths = []
          view_endpoints = []
          for path, method, callback in self.endpoints:
              view = self.create_view(callback, method, request)
              if getattr(view, 'exclude_from_schema', False):
                  continue
              path = self.coerce_path(path, method, view)
              paths.append(path)
              view_endpoints.append((path, method, view))
  
          # Only generate the path prefix for paths that will be included
          if not paths:
              return None
          prefix = self.determine_path_prefix(paths)
  
          for path, method, view in view_endpoints:
              if not self.has_view_permissions(path, method, view):
                  continue
              link = self.get_link(path, method, view, version=getattr(request, 'version', None))
              subpath = path[len(prefix):]
              keys = self.get_keys(subpath, method, view)
              try:
                  insert_into(links, keys, link)
              except Exception:
                  continue
          return links
docs: Return a dictionary containing all the links that should be
          included in the API schema.