No, you are miles away from an efficient approach. You need to figure out another way to count primes.

Got it

Are the test cases always going to be primes, or do I have to check for that too?

The part where the function is called without an argument, like you need to do here. Just scroll a little bit and you'll find it.

Uh... Which part?

I honestly have no idea how to do that. I tried a loop, but...

Now you have to work out, how you can make the code work if no argument is passed to it.

And.... now it gives me a TypeError, like last time.

How?

You probably edited the sample tests, backup your code, click Reset, paste it and try again. Not a kata issue, the sample tests are fine in Python.