That's just how the site works: the tests require your function to return a value. That value is use to check for a valid alogithm. :)

Ok i got the code right. But what i dont get is why printing the statement was not accepted??

For every test it is returning None.

That's because your code is printing instead of returning. Read this: https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution