Dynamic SQL in SQL/PSM samples

EXECUTE IMMEDIATE INTO

CREATE OR REPLACE FUNCTION fx() 
RETURNS int AS 
$$
  BEGIN 
    DECLARE a,b int; 
    EXECUTE IMMEDIATE 'SELECT 10,20' INTO a,b; 
    PRINT a,b; 
    RETURN a+b; 
  END; 
$$ LANGUAGE plpgpsm;

PREPARE/EXECUTE INTO USING

CREATE OR REPLACE FUNCTION fxx(a int)
RETURNS float AS 
$$
  BEGIN
    DECLARE f float;
    PREPARE prep(float) from 'select $1';
    EXECUTE prep INTO f USING a; 
    RETURN f ;
  END;
$$ LANGUAGE plpgpsm;