Launch the screensaver.

    CLI Example:

    .. code-block:: bash

        salt '*' desktop.screensaver

def screensaver():
    '''
    Launch the screensaver.

    CLI Example:

    .. code-block:: bash

        salt '*' desktop.screensaver
    '''
    cmd = 'open /System/Library/Frameworks/ScreenSaver.framework/Versions/A/Resources/ScreenSaverEngine.app'
    call = __salt__['cmd.run_all'](
        cmd,
        output_loglevel='debug',
        python_shell=False
    )
    _check_cmd(call)

    return True