Update all the Index instances attached to this model (if their
        ignore_signals flag allows it)

def update(self, instance, **kwargs):
        """
        Update all the Index instances attached to this model (if their
        ignore_signals flag allows it)
        """
        for index in self.model_to_indexes[instance.__class__]:
            if not index._doc_type.ignore_signals:
                index.update(instance, **kwargs)