Python is_prime using Miller-Rabin

from random import randrange

def is_prime(n, trials=6):
    """ Miller-Rabin probabilistic prime test.
    """
    if n < 2:
        return False
    i = 0
    while i < trials:
        i+=1
        a = randrange(1, n)
        if pow(a, n-1, n) != 1: # (a**(n-1)) % n
            return False
    return True

# or as a tiny-font-one-liner


def is_prime(n, trials=6):
    return n >= 2 and (trials == 0 or (pow(randrange(1, n), n-1, n) == 1 and is_prime(n, trials - 1)))