My database is hosted in Amazon and I am using pgAdmin 4 to connect to it. I copy-pasted snippet from https://www.postgresql.org/docs/11/sql-createprocedure.html
CREATE PROCEDURE insert_data(a integer, b integer)
LANGUAGE SQL
AS $$
INSERT INTO tbl VALUES (a);
INSERT INTO tbl VALUES (b);
$$;
The issue is that I get 'incorrect syntax near 'PROCEDURE' ' error

What is done wrong? Not sure how I check version of postgresql itself