CREATE PROCEDURE test_proc1()
LANGUAGE pltcl
AS $$
unset
$$;
CALL test_proc1();
CREATE PROCEDURE test_proc2()
LANGUAGE pltcl
AS $$
return 5
$$;
CALL test_proc2();
CREATE TABLE test1 (a int);
CREATE PROCEDURE test_proc3(x int)
LANGUAGE pltcl
AS $$
spi_exec "INSERT INTO test1 VALUES ($1)"
$$;
CALL test_proc3(55);
SELECT * FROM test1;
 a  
----
 55
(1 row)

-- output arguments
CREATE PROCEDURE test_proc5(INOUT a text)
LANGUAGE pltcl
AS $$
set aa [concat $1 "+" $1]
return [list a $aa]
$$;
CALL test_proc5('abc');
     a     
-----------
 abc + abc
(1 row)

CREATE PROCEDURE test_proc6(a int, INOUT b int, INOUT c int)
LANGUAGE pltcl
AS $$
set bb [expr $2 * $1]
set cc [expr $3 * $1]
return [list b $bb c $cc]
$$;
CALL test_proc6(2, 3, 4);
 b | c 
---+---
 6 | 8
(1 row)

-- OUT parameters
CREATE PROCEDURE test_proc9(IN a int, OUT b int)
LANGUAGE pltcl
AS $$
elog NOTICE "a: $1"
return [list b [expr {$1 * 2}]]
$$;
DO $$
DECLARE _a int; _b int;
BEGIN
  _a := 10; _b := 30;
  CALL test_proc9(_a, _b);
  RAISE NOTICE '_a: %, _b: %', _a, _b;
END
$$;
NOTICE:  a: 10
NOTICE:  _a: 10, _b: 20
DROP PROCEDURE test_proc1;
DROP PROCEDURE test_proc2;
DROP PROCEDURE test_proc3;
DROP TABLE test1;