Most likely you're trying to iterate over an integer, like so:
`for x, y in sequence:

do stuff`

To fix that, you'd write
`for x, y in enumerate(sequence):

do stuff`

Are you talking about the situation where your code passes the tests but you don't get the SUBMIT FINAL button? That happens to me on Codewars sometimes ... when it does, I copy my solution code to the clipboard, then do shift-reload to reload the browser window, then replace the code in the Solution box (which reloading may have reverted to a previous version) with the code I copied, then run the tests again. Then you should get the congratulations message and the SUBMIT FINAL button.

Thanks/You're welcome!