def prompt_to_top(self):
        """ Moves the prompt to the top of the viewport.
        """
        if not self._executing:
            prompt_cursor = self._get_prompt_cursor()
            if self._get_cursor().blockNumber() < prompt_cursor.blockNumber():
                self._set_cursor(prompt_cursor)
            self._set_top_cursor(prompt_cursor)
Moves the prompt to the top of the viewport.