code: def search_assignable_users_for_issues(self,
                                             username,
                                             project=None,
                                             issueKey=None,
                                             expand=None,
                                             startAt=0,
                                             maxResults=50,
                                             ):
          
          params = {
              'username': username}
          if project is not None:
              params['project'] = project
          if issueKey is not None:
              params['issueKey'] = issueKey
          if expand is not None:
              params['expand'] = expand
          return self._fetch_pages(User, None, 'user/assignable/search', startAt, maxResults, params)
docs: Get a list of user Resources that match the search string for assigning or creating issues.
  
          This method is intended to find users that are eligible to create issues in a project or be assigned
          to an existing issue. When searching for eligible creators, specify a project. When searching for eligible
          assignees, specify an issue key.
  
          :param username: A string to match usernames against
          :type username: str
          :param project: Filter returned users by permission in this project (expected if a result will be used to
              create an issue)
          :type project: Optional[str]
          :param issueKey: Filter returned users by this issue (expected if a result will be used to edit this issue)
          :type issueKey: Optional[str]
          :param expand: Extra information to fetch inside each resource
          :type expand: Optional[Any]
          :param startAt: Index of the first user to return (Default: 0)
          :type startAt: int
          :param maxResults: maximum number of users to return.
                  If maxResults evaluates as False, it will try to get all items in batches. (Default: 50)
  
          :rtype: ResultList