docs: def iter_annotations(self):
          """Yield a tuple for each Flask handler containing annotated methods.
  
          Each tuple contains a heading, routing rule, the view class associated
          with the rule, and the annotations for the methods in that class.
          """
          # Need to store a list of route, view_class, and annotations by a
          # section key so that all methods of a resource are kept together in
          # the documentation.  The key of the section will be the heading that
          # the route documentation goes under.
          section_map = defaultdict(list)
          for rule in self.app.url_map.iter_rules():
              if rule.endpoint == 'static':
                  # Don't document static file endpoints.
                  continue
              # This gives us the auto-generated view function.
              view_function = self.app.view_functions.get(rule.endpoint)
              if view_function is None:
                  continue
              # This gives us the actual Flask resource class.
              view_class = getattr(view_function, 'view_class', None)
              if view_class is None:
                  continue
  
              annotations = []
              for method_name in HTTP_METHODS:
                  method = getattr(view_class, method_name, None)
                  if not method:
                      continue
                  annotation = ResourceAnnotation(
                      method, method_name, method._doctor_title)
                  annotations.append(annotation)
              if annotations:
                  heading = self._get_annotation_heading(view_class, str(rule))
                  section_map[heading].append((rule, view_class, annotations))
  
          # Loop through each heading and it's items and yield the values.
          for heading in sorted(section_map.keys()):
              for item in section_map[heading]:
                  rule, view_class, annotations = item
                  yield (heading, rule, view_class, annotations)