Request an update of the memory content

def update(self, update_finished_cb):
        """Request an update of the memory content"""
        if not self._update_finished_cb:
            self._update_finished_cb = update_finished_cb
            self.valid = False
            logger.debug('Updating content of memory {}'.format(self.id))
            # Start reading the header
            self.mem_handler.read(self, 0, 11)