The tests assume that there can be only one way to solve the problem: if the number is even, divide it by 2 and if the number is odd, multiply it by 3 and add 1.

Multiplying by 3 and adding 1 can cause an overflow, which the tests accommodate by allowing `None`

as a correct response whenever `u64`

overflows occur.

The problem is that `None`

is considered to be * the only* correct response in that case, when every nonzero

`u64`

has a correct answer that can be put into `Some`

. For example, overflow can be avoided by converting the input `u64`

into a `u128`

and then getting the result using `u128`

arithmetic.This commit corrects the tests so that either `None`

or the correct answer is allowed when `u64`

overflow can occur. All code that already passed the old tests will also pass the corrected tests.

The changes can be seen at the pull request.