def flag(
        self,
        flag_data: list[Any],
        flag_option: str | None = None,
        username: str | None = None,
    ) -> int:
        """
        This method should be overridden by the FlaggingCallback subclass and may contain optional additional arguments.
        This gets called every time the <flag> button is pressed.
        Parameters:
        interface: The Interface object that is being used to launch the flagging interface.
        flag_data: The data to be flagged.
        flag_option (optional): In the case that flagging_options are provided, the flag option that is being used.
        username (optional): The username of the user that is flagging the data, if logged in.
        Returns:
        (int) The total number of samples that have been flagged.
        """
        pass

        This method should be overridden by the FlaggingCallback subclass and may contain optional additional arguments.
        This gets called every time the <flag> button is pressed.
        Parameters:
        interface: The Interface object that is being used to launch the flagging interface.
        flag_data: The data to be flagged.
        flag_option (optional): In the case that flagging_options are provided, the flag option that is being used.
        username (optional): The username of the user that is flagging the data, if logged in.
        Returns:
        (int) The total number of samples that have been flagged.
        
gradio/flagging.py