def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def get_target_input(module, input, output):
    """A forward hook which saves the tensor - attached to its graph.
    Used if we want to explain the interim outputs of a model
    """
    try:
        del module.target_input
    except AttributeError:
        pass
    setattr(module, 'target_input', input)