before setting property
    value of prop: undefined
    is prop enumerable: false
after setting property
    value of prop: 99
    is prop enumerable: true
    prop iterated over
after making property not-enumerable
    value of prop: 99
    is prop enumerable: false
after re-setting property
    value of prop: 99
    is prop enumerable: false
after re-setting property (2)
    value of prop: 89
    is prop enumerable: false
after deleting property
    value of prop: undefined
    is prop enumerable: false
after re-setting property (3)
    value of prop: 12
    is prop enumerable: true
    prop iterated over
