docs: def get_all_assignable_users_for_project(self, project_key, start=0, limit=50):
          """
          Provide assignable users for project
          :param project_key:
          :param start: OPTIONAL: The start point of the collection to return. Default: 0.
          :param limit: OPTIONAL: The limit of the number of users to return, this may be restricted by
                  fixed system limits. Default by built-in method: 50
          :return:
          """
          url = 'rest/api/2/user/assignable/search?project={project_key}&startAt={start}&maxResults={limit}'.format(
              project_key=project_key,
              start=start,
              limit=limit)
          return self.get(url)