public FEELFnResult<String> invoke(@ParameterName("from") Object val) {
        if ( val == null ) {
            return FEELFnResult.ofResult( null );
        } else {
            return FEELFnResult.ofResult( TypeUtil.formatValue(val, false) );
        }
    }
@Test
    void invokeRangeClosedOpen() {
        FunctionTestUtil.assertResult(
                stringFunction.invoke(new RangeImpl(Range.RangeBoundary.CLOSED, 12, 15, Range.RangeBoundary.OPEN)),
                "[ 12 .. 15 )");
    }