proposal: PLpgSQL parallel assignemnt

Hi

Some modern or old languages (GO, Lua, CLU) has similarly designed function
OUT parameters like PLpgSQL.

In these languages is usually supported parallel assignment. It is not
supported by PLpgSQL - there is workaround - using SELECT FROM, but it is
workaround. The implementation of PA is trivial.

Current state:
==========

CREATE OR REPLACE FUNCTION fx(OUT a int, OUT b int)
AS $$ ...

possibilities of CALL and assignment

recvar := fx();
rowvar := fx();

SELECT * FROM fx() INTO a, b;

Lua, Golang like proposal:

a, b := fx();

Comments, notes, ideas?

Regards

Pavel