'Fetch firewall rules for a network interface.
:param network_interface: The network interface.
:type network_interface: :class:`ProfitBricksNetworkInterface`
:return:    ``list`` of class ``ProfitBricksFirewallRule``
:rtype:     `list`'

def ex_list_firewall_rules(self, network_interface):

    action = (network_interface.href + '/firewallrules')
    response = self.connection.request(action=action, method='GET', params={'depth': 3}, with_full_url=True)
    return self._to_firewall_rules(response.object)
