#[(9, false), (8, true), (7, false), (6, true), (5, false), (4, true), (3, false), (2, true), (1, false), (0, true)]
>> 0 ==> (some (0, true))
>> 1 ==> (some (1, false))
>> 2 ==> (some (2, true))
>> 3 ==> (some (3, false))
>> 4 ==> (some (4, true))
>> 5 ==> (some (5, false))
>> 6 ==> (some (6, true))
>> 7 ==> (some (7, false))
>> 8 ==> (some (8, true))
>> 9 ==> (some (9, false))
>> 10 ==> none
>> 11 ==> none
>> 12 ==> none
>> 13 ==> none
>> 14 ==> none
>> 15 ==> none
>> 16 ==> none
>> 17 ==> none
>> 18 ==> none
>> 19 ==> none