def custom_resolve(self):
if not callable(self.custom_resolver):<EOL><INDENT>return<EOL><DEDENT>new_addresses = []<EOL>for address in self.addresses:<EOL><INDENT>for new_address in self.custom_resolver(address):<EOL><INDENT>new_addresses.append(new_address)<EOL><DEDENT><DEDENT>self.addresses = new_addresses<EOL>
If a custom resolver is defined, perform custom resolution on
        the contained addresses.

        :return: