docs: def get_issue_by_ref(self, ref):
          """
          Get a :class:`Issue` by ref.
  
          :param ref: :class:`Issue` reference
          """
          response = self.requester.get(
              '/{endpoint}/by_ref?ref={us_ref}&project={project_id}',
              endpoint=Issue.endpoint,
              us_ref=ref,
              project_id=self.id
          )
          return Issue.parse(self.requester, response.json())