<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def remove_ifcfg_file(device_index='0'):
 """Removes the ifcfg file at the specified device index and restarts the network service :param device_index: (int) Device Index :return: None :raises CommandError """

    log = logging.getLogger(mod_logger + '.remove_ifcfg_file')
    if not isinstance(device_index, basestring):
        msg = 'device_index argument must be a string'
        log.error(msg)
        raise CommandError(msg)
    network_script = '/etc/sysconfig/network-scripts/ifcfg-eth{d}'.format(d=device_index)
    if not os.path.isfile(network_script):
        log.info('File does not exist, nothing will be removed: {n}'.format(n=network_script))
        return

    # Remove the network config script
    log.info('Attempting to remove file: {n}'.format(n=network_script))
    try:
        os.remove(network_script)
    except(IOError, OSError):
        _, ex, trace = sys.exc_info()
        msg = 'There was a problem removing network script file: {n}\n{e}'.format(n=network_script, e=str(ex))
        log.error(msg)
        raise OSError, msg, trace
    else:
        log.info('Successfully removed file: {n}'.format(n=network_script))

    # Restart the network service
    log.info('Restarting the network service...')
    try:
        service_network_restart()
    except CommandError:
        _, ex, trace = sys.exc_info()
        msg = 'There was a problem restarting the network service\n{e}'.format(e=str(ex))
        log.error(msg)
        raise OSError, msg, trace
    else:
        log.info('Successfully restarted the network service')