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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def list_global_ips(self, version=None, identifier=None, **kwargs):
 """Returns a list of all global IP address records on the account. :param int version: Only returns IPs of this version (4 or 6) :param string identifier: If specified, the list will only contain the global ips matching this network identifier. """

        if 'mask' not in kwargs:
            mask = ['destinationIpAddress[hardware, virtualGuest]',
                    'ipAddress']
            kwargs['mask'] = ','.join(mask)

        _filter = utils.NestedDict({})

        if version:
            ver = utils.query_filter(version)
            _filter['globalIpRecords']['ipAddress']['subnet']['version'] = ver

        if identifier:
            subnet_filter = _filter['globalIpRecords']['ipAddress']['subnet']
            subnet_filter['networkIdentifier'] = utils.query_filter(identifier)

        kwargs['filter'] = _filter.to_dict()
        return self.account.getGlobalIpRecords(**kwargs)