C01P06 - NaN expand

In most programming languages, NaN stands for Not a Number.

If we take a look at the following JavaScript code:

typeof NaN === 'number'; // true

We will see that in JavaScript, NaN stands for Not a NaN, which is recursive by nature.

Implement a Python function, called nan_expand(times), which returns the expansion of NaN (In JavaScript terms) that many times.

Here's the signature:

def nan_expand(times):
    pass

Examples:

1. If we expand NaN once (times=1), we will have "Not a NaN"
2. If we expand NaN twice (times=2), we will have "Not a Not a NaN"
3. If times=3, we have "Not a Not a Not a NaN"
4. And so on ...

nan_expand(0) == ""
nan_expand(1) == "Not a NaN"
nan_expand(2) == "Not a Not a NaN"
nan_expand(3) == "Not a Not a Not a NaN"