def pause(message='<STR_LIT>'):
key = None<EOL>print(message, end='<STR_LIT:U+0020>', flush=True)<EOL>if is_a_tty():  <EOL><INDENT>key = wait_key()<EOL><DEDENT>print()<EOL>return key<EOL>
Analogous to the ancient
        `DOS pause <https://en.wikipedia.org/wiki/List_of_DOS_commands#PAUSE>`_
        command, with a modifiable message.

        Arguments:
            message:  str

        Returns:
            str, None:  One character or ESC - depending on key hit.
            None - immediately under i/o redirection, not an interactive tty.