public Result parse(final String string) throws DateNotParsableException {
        return this.parse(string, new Date());
    }
@Test
    public void testLast4hours() throws Exception {
        DateTime reference = DateTime.now(DateTimeZone.UTC);
        NaturalDateParser.Result last4 = naturalDateParser.parse("last 4 hours", reference.toDate());
        assertThat(last4.getFrom()).as("from should be exactly 4 hours in the past").isEqualTo(reference.minusHours(4));
        assertThat(last4.getTo()).as("to should be the reference date").isEqualTo(reference);
    }