Reboot the system

    at_time
        The wait time in minutes before the system will be rebooted.

    CLI Example:

    .. code-block:: bash

        salt '*' system.reboot

def reboot(at_time=None):
    '''
    Reboot the system

    at_time
        The wait time in minutes before the system will be rebooted.

    CLI Example:

    .. code-block:: bash

        salt '*' system.reboot
    '''
    cmd = ['shutdown', '-r', ('{0}'.format(at_time) if at_time else 'now')]
    ret = __salt__['cmd.run'](cmd, python_shell=False)
    return ret