code: def list_instances(self):
          
          # Server does not do pagination on listings of this resource.
          # Return an iterator anyway for similarity with other API methods
          response = self.get_proto(path='/instances')
          message = rest_pb2.ListInstancesResponse()
          message.ParseFromString(response.content)
          instances = getattr(message, 'instance')
          return iter([Instance(instance) for instance in instances])
docs: Lists the instances.
  
          Instances are returned in lexicographical order.
  
          :rtype: ~collections.Iterable[.Instance]