Instructions: You can solve this in your favorite language:
Task: Make a function that can take any non-negative integer as an argument and return it with its digits in descending order. Essentially, rearrange the digits to create the highest possible number.
**Result Examples:
```
Input: 42145 Output: 54421
Input: 145263 Output: 654321
Input: 123456789 Output: 987654321
``` 