The Collatz Conjecture or 3x+1 problem can be summarized as follows:

Take any positive integer n. If n is even, divide n by 2 to get n / 2. If n is odd, multiply n by 3 and add 1 to get 3n + 1. Repeat the process indefinitely. The conjecture states that no matter which number you start with, you will always reach 1 eventually.

Given a number n, return the number of steps required to reach 1.

(Keep in mind that the Conjecture is only concerned with strictly positive integers, so your solution should return None if given 0 or a negative integer.)

Starting with n = 3, the steps would be as follows:

0. 3
1. 10
2. 5
3. 16
4. 8
5. 4
6. 2
7. 1

Resulting in 7 steps. So for input n = 3, the return value would be 7.

Starting with n = 12, the steps would be as follows:

0. 12
1. 6
2. 3
3. 10
4. 5
5. 16
6. 8
7. 4
8. 2
9. 1

Resulting in 9 steps. So for input n = 12, the return value would be 9.

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An unsolved problem in mathematics named after mathematician Lothar Collatz https://en.wikipedia.org/wiki/3x_%2B_1_problem

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