This command on the model allow getting many instancehash fields with only
        one redis call. You must pass hash name to retrieve as arguments.

def hmget(self, *args):
        """
        This command on the model allow getting many instancehash fields with only
        one redis call. You must pass hash name to retrieve as arguments.
        """
        if args and not any(arg in self._instancehash_fields for arg in args):
            raise ValueError("Only InstanceHashField can be used here.")

        return self._call_command('hmget', args)