'For a given resource_group build a mapping of network_interface.id to security_group name'

def _get_security_groups(self, resource_group):

    if (not self._security_groups):
        self._security_groups = dict()
    if (not self._security_groups.get(resource_group)):
        self._security_groups[resource_group] = dict()
        for group in self._network_client.network_security_groups.list(resource_group):
            if group.network_interfaces:
                for interface in group.network_interfaces:
                    self._security_groups[resource_group][interface.id] = dict(name=group.name, id=group.id)
