code: def setPollFDNotifiers(
              self, added_cb=None, removed_cb=None, user_data=None):
          
          if added_cb is None:
              added_cb = self.__null_pointer
          else:
              added_cb = libusb1.libusb_pollfd_added_cb_p(added_cb)
          if removed_cb is None:
              removed_cb = self.__null_pointer
          else:
              removed_cb = libusb1.libusb_pollfd_removed_cb_p(removed_cb)
          if user_data is None:
              user_data = self.__null_pointer
          self.__added_cb = added_cb
          self.__removed_cb = removed_cb
          self.__poll_cb_user_data = user_data
          self.__libusb_set_pollfd_notifiers(
              self.__context_p,
              self.__cast(added_cb, libusb1.libusb_pollfd_added_cb_p),
              self.__cast(removed_cb, libusb1.libusb_pollfd_removed_cb_p),
              user_data,
          )
docs: Give libusb1 methods to call when it should add/remove file descriptor
          for polling.
          You should not have to call this method, unless you are integrating
          this class with a polling mechanism.