How to use the capirca.lib.nacaddr function in capirca

return '\n'.join(ret_str)

    # protocol
    if not self.term.protocol:
      protocol = ['ip']
    else:
      # fix the protocol
      protocol = self.term.protocol

    # source address
    if self.term.source_address:
      source_address = self.term.GetAddressOfVersion('source_address', self.af)
      source_address_exclude = self.term.GetAddressOfVersion(
          'source_address_exclude', self.af)
      if source_address_exclude:
        source_address = nacaddr.ExcludeAddrs(
            source_address,
            source_address_exclude)
    else:
      # source address not set
      source_address = ['any']

    # destination address
    if self.term.destination_address:
      destination_address = self.term.GetAddressOfVersion(
          'destination_address', self.af)
      destination_address_exclude = self.term.GetAddressOfVersion(
          'destination_address_exclude', self.af)
      if destination_address_exclude:
        destination_address = nacaddr.ExcludeAddrs(
            destination_address,
            destination_address_exclude)

def _GetIpString(self, addr):
    """Formats the address object for printing in the ACL.

    Args:
      addr: str or ipaddr, address
    Returns:
      An address string suitable for the ACL.
    """
    if isinstance(addr, nacaddr.IPv4) or isinstance(addr,
                                                    ipaddress.IPv4Network):
      if addr.num_addresses > 1:
        if self.platform == 'arista':
          return addr.with_prefixlen
        return '%s %s' % (addr.network_address, addr.hostmask)
      return 'host %s' % (addr.network_address)
    if isinstance(addr, nacaddr.IPv6) or isinstance(addr,
                                                    ipaddress.IPv6Network):
      if addr.num_addresses > 1:
        return addr.with_prefixlen
      return 'host %s' % (addr.network_address)
    # DSMO enabled
    if isinstance(addr, summarizer.DSMNet):
      return '%s %s' % summarizer.ToDottedQuad(addr, negate=True)
    return addr

"""Reduce source, dest, and address fields to their post-exclude state.

    Populates the self.flattened_addr, self.flattened_saddr,
    self.flattened_daddr by removing excludes from includes.
    """
    # No excludes, set flattened attributes and move along.
    self.flattened = True
    if not (self.source_address_exclude or self.destination_address_exclude or
            self.address_exclude):
      self.flattened_saddr = self.source_address
      self.flattened_daddr = self.destination_address
      self.flattened_addr = self.address
      return

    if self.source_address_exclude:
      self.flattened_saddr = nacaddr.AddressListExclude(
          self.source_address,
          self.source_address_exclude,
          collapse_addrs=False)
      self.source_address = self.flattened_saddr
    if self.destination_address_exclude:
      self.flattened_daddr = nacaddr.AddressListExclude(
          self.destination_address,
          self.destination_address_exclude,
          collapse_addrs=False)
      self.destination_address = self.flattened_daddr
    if self.address_exclude:
      self.flattened_addr = nacaddr.AddressListExclude(
          self.address, self.address_exclude, collapse_addrs=False)
      self.address = self.flattened_addr

if filter_options:
        network = filter_options[0]
      else:
        logging.warn('GCE filter does not specify a network.')

      term_names = set()
      if IsDefaultDeny(terms[-1]):
        terms[-1].protocol = ['all']
        terms[-1].priority = 65534
        if direction == 'EGRESS':
          terms[-1].destination_address = [nacaddr.IP('0.0.0.0/0'),
                                           nacaddr.IP('::/0')]
        else:
          terms[-1].source_address = [
              nacaddr.IP('0.0.0.0/0'),
              nacaddr.IP('::/0')
          ]

      for term in terms:
        if term.stateless_reply:
          logging.warn('WARNING: Term %s in policy %s is a stateless reply '
                       'term and will not be rendered.',
                       term.name, filter_name)
          continue
        term.network = network
        if not term.comment:
          term.comment = header.comment
        term.name = self.FixTermLength(term.name)
        if term.name in term_names:
          raise GceFirewallError('Duplicate term name')
        term_names.add(term.name)