def supports_sync(self) -> bool:
        """Whether this extension can be resolved synchronously or not.

        The Permission extension always supports async checking using await_maybe,
        but only supports sync checking if there are no async permissions.
        """
        async_permissions = [
            True
            for permission in self.permissions
            if iscoroutinefunction(permission.has_permission)
        ]
        return len(async_permissions) == 0
Whether this extension can be resolved synchronously or not.

        The Permission extension always supports async checking using await_maybe,
        but only supports sync checking if there are no async permissions.
        
strawberry/permission.py