Closes this cursor.

def __die(self, synchronous=False):
        """Closes this cursor.
        """
        if self.__id and not self.__killed:
            if self.__exhaust and self.__exhaust_mgr:
                # If this is an exhaust cursor and we haven't completely
                # exhausted the result set we *must* close the socket
                # to stop the server from sending more data.
                self.__exhaust_mgr.sock.close()
            else:
                address = _CursorAddress(
                    self.__address, self.__collection.full_name)
                if synchronous:
                    self.__collection.database.client._close_cursor_now(
                        self.__id, address)
                else:
                    self.__collection.database.client.close_cursor(
                        self.__id, address)
        if self.__exhaust and self.__exhaust_mgr:
            self.__exhaust_mgr.close()
        self.__killed = True