boolean return type from function

How to get boolean return type from function?

CREATE OR REPLACE FUNCTION F_Is_Even(i_number IN NUMBER)
RETURN BOOLEAN
AS
/*
DECLARE
b1 BOOLEAN;
v1 VARCHAR2(10);
BEGIN
b1 :=F_Is_Even(10);
IF (b1) THEN
v1 :='TRUE';
ELSE
v1 :='FALSE';
END IF;
dbms_output.put_line(v1);
END;


*/
v1 VARCHAR2(10);
v2 BOOLEAN;
BEGIN
SELECT DECODE(MOD(i_number,2),0,'TRUE',1,'FALSE','FALSE') INTO v1 FROM dual;
IF v1='TRUE' THEN
v2 :=TRUE;
ELSE
v2 :=FALSE;
END IF;
RETURN v2;
END;
/