docs: def requestAttribute(self, attrib: Attribute, sender):
          """
          Used to get a raw attribute from Sovrin
          :param attrib: attribute to add
          :return: number of pending txns
          """
          self._attributes[attrib.key()] = attrib
          req = attrib.getRequest(sender)
          if req:
              return self.prepReq(req, key=attrib.key())