guest example: is_prime

[icemelon]

for i in 2..sqrt(n):
  if n % i == 0:
    return false
return true

[matthiasgoergens]

I removed @naure from the title and put him as an assignee.

[matthiasgoergens]

https://en.wikipedia.org/wiki/Primality_certificate might be a fun thing to add, especially if there's already a Rust library.