def stop(watson, at_):
    """
    Stop monitoring time for the current project.

    If `--at` option is given, the provided stopping time is used. The
    specified time must be after the beginning of the to-be-ended frame and must
    not be in the future.

    Example:

    \b
    $ watson stop --at 13:37
    Stopping project apollo11, started an hour ago and stopped 30 minutes ago. (id: e9ccd52) # noqa: E501
    """
    frame = watson.stop(stop_at=at_)
    output_str = "Stopping project {}{}, started {} and stopped {}. (id: {})"
    click.echo(output_str.format(
        style('project', frame.project),
        (" " if frame.tags else "") + style('tags', frame.tags),
        style('time', frame.start.humanize()),
        style('time', frame.stop.humanize()),
        style('short_id', frame.id),
    ))
    watson.save()

    Stop monitoring time for the current project.

    If `--at` option is given, the provided stopping time is used. The
    specified time must be after the beginning of the to-be-ended frame and must
    not be in the future.

    Example:

    
    $ watson stop --at 13:37
    Stopping project apollo11, started an hour ago and stopped 30 minutes ago. (id: e9ccd52) # noqa: E501
    
watson/cli.py