Returns true if the device is reachable, else false.

def ping():
    '''
    Returns true if the device is reachable, else false.
    '''
    try:
        session, cookies, csrf_token = logon()
        logout(session, cookies, csrf_token)
    except salt.exceptions.CommandExecutionError:
        return False
    except Exception as err:
        log.debug(err)
        return False
    return True