public MemorySize divide(long by) {
        if (by < 0) {
            throw new IllegalArgumentException("divisor must be != 0");
        }
        return new MemorySize(bytes / by);
    }
@Test
    void testDivideByNegativeLong() {
        assertThatExceptionOfType(IllegalArgumentException.class)
                .isThrownBy(
                        () -> {
                            final MemorySize memory = new MemorySize(100L);
                            memory.divide(-23L);
                        });
    }