'Lists the instances in the specified instance group.
Scopes needed - one of the following:
* https://www.googleapis.com/auth/cloud-platform
* https://www.googleapis.com/auth/compute
* https://www.googleapis.com/auth/compute.readonly
:param  instancegroup:  The Instance Group where from which you
want to generate a list of included
instances.
:type   instancegroup: :class:`GCEInstanceGroup`
:return:  List of :class:`GCENode` objects.
:rtype: ``list`` of :class:`GCENode` objects.'

def ex_instancegroup_list_instances(self, instancegroup):

    request = ('/zones/%s/instanceGroups/%s/listInstances' % (instancegroup.zone.name, instancegroup.name))
    response = self.connection.request(request, method='POST').object
    list_data = []
    if ('items' in response):
        for v in response['items']:
            instance_info = self._get_components_from_path(v['instance'])
            list_data.append(self.ex_get_node(instance_info['name'], instance_info['zone']))
    return list_data
