Enable the list of network interfaces.

    Args:
      interfaces: list of string, the output device names to enable.
      logger: logger object, used to write to SysLog and serial port.
      dhclient_script: string, the path to a dhclient script used by dhclient.

def EnableNetworkInterfaces(
      self, interfaces, logger, dhclient_script=None):
    """Enable the list of network interfaces.

    Args:
      interfaces: list of string, the output device names to enable.
      logger: logger object, used to write to SysLog and serial port.
      dhclient_script: string, the path to a dhclient script used by dhclient.
    """
    helpers.CallDhclient(interfaces, logger, dhclient_script=dhclient_script)