code: def list(self, limit=None, marker=None, return_next=False):
          
          kwargs = {}
          if return_next:
              kwargs["other_keys"] = "metadata"
          ret = super(_PaginationManager, self).list(limit=limit,
                  marker=marker, **kwargs)
          if return_next:
              ents, meta = ret
              return (ents, meta[0].get("next_marker"))
          else:
              return ret
docs: This is necessary to handle pagination correctly, as the Monitoring
          service defines 'marker' differently than most other services. For
          monitoring, 'marker' represents the first item in the next page,
          whereas other services define it as the ID of the last item in the
          current page.