it('deeply detects a new value', () => {
    expectSame({ deep: { inside: { xnum: 0 } } })
    expectSame({ deep: { inside: { xobj: { x: 0 } } } })
    expectSame({ deep: { inside: { xarray: [0] } } })
    expectSame({ deep: { inside: { xdate: new Date() } } })