How to remove Unnecessary Spaces

CREATE FUNCTION remove_unwanted_spaces( in_value IN VARCHAR2 )
RETURN VARCHAR2
AS
v_result VARCHAR2(32767);
BEGIN
IF( in_value IS NOT NULL ) THEN
FOR i IN 1 .. ( LENGTH(in_value) - 1 ) LOOP
IF( SUBSTR( in_value, i, 2 ) <> ' ' ) THEN
v_result := v_result SUBSTR( in_value, i, 1 );
END IF;
END LOOP;
v_result := v_result SUBSTR( in_value, -1 );
END IF;
RETURN v_result;
END;