[threatripper]

Let me repeat if I understand it right:

* The function will return True for all primes.

* The function will return False if the number is detected as a composite by some tests.

* The function can return True or False for all other numbers.

* For numbers<=23 they implemented a shortcut using a lookup table which is implemented as bits in a number.

* The bit for number 19 is wrong. It returns false for a prime number which violates "return True for all prime numbers".

This is indeed quite shoddy programming for such an essential and easily testable piece of software.

[vmilner]

It’s not easily testable if it’a pseudocode that hasn’t been implemented yet.