docs: def get_letter_status(self, pixelletter_id):
          """
          :param pixelletter_id: ID of the letter
          :return: dict containing status of the requested letter
          """
          letter_status = self._make_get_request('letters/{}'.format(pixelletter_id))
  
          if letter_status:
              return json.loads(letter_status)
  
          return None