After I submitted my solution I realized it doesn't work if the gnerator not a range (i.e. 1,5,32,4). It might be a good idea to add test cases if you want to keep with that earlier requirement. Also, what other people where saying about the prime numbers- The prime number function in the tests needs a guard clause for 1 (and tests updated). Loving this series by the way!

Not a kata issue - it's a question.

Btw, the code works fine...