Please find below working example -
CREATE OR REPLACE PROCEDURE generateTime(integer)
LANGUAGE NZPLSQL RETURNS varchar(255) AS
BEGIN_PROC
DECLARE
p_abc integer;
p_bcd integer;
p_var1 ALIAS FOR $1;
BEGIN
p_bcd := ISNULL(p_var1, 10);
raise notice 'p_bcd=%',p_bcd;
FOR p_abc in 0..(p_bcd)
LOOP
raise notice 'Hello World %', p_abc;
END LOOP;
END;
END_PROC;
Hope this will help.