PL/python event_trigger

It seems event triggers can not be writen in plypython3u

CREATE OR REPLACE FUNCTION log_schema_changes()

RETURNS EVENT_TRIGGER

LANGUAGE plpython3u

 AS $$

import plpy

plyp.warning(TD)

$$;

Generates error “ERROR:  trigger functions can only be called as triggers”

Version info is: psql (15.6 (Ubuntu 15.6-1.pgdg20.04+1), server 15.7 (Ubuntu 15.7-1.pgdg22.04+1))