
Write the `getNumberExplanation()` function that describes an input number passed to it. If there is no explanation available, it returns `just a number`:

```javascript
getNumberExplanation(8);   // just a number

// Only the following numbers have descriptions
getNumberExplanation(666); // devil number
getNumberExplanation(42);  // answer for everything
getNumberExplanation(7);   // prime number
```
