This is my solution for the assignment at the end of Chapter 3 in "Automate the Boring Stuff with Python" - a simple program for executing the collatz sequence. If you don't know what the collatz sequence is, check out its Wikipedia entry.

The program allows the user to enter any postive number.
If the input is valid (see below), it is converted into an integer and passed into the collatz function.
The collatz function checks if the current integer is even or odd:

• if it is odd, it gets multiplied by 3 and then 1 is added
• if it is even, it gets divided by 2 with floor division to prevent a floating number

Prevents the following situations:

• a string or symbol being entered
• a negative number being entered