def are_relatively_prime(a, b):
    """Return ``True`` if ``a`` and ``b`` are two relatively prime numbers.

    Two numbers are relatively prime if they share no common factors,
    i.e. there is no integer (except 1) that divides both.
    """
    for n in range(2, min(a, b) + 1):
        if a % n == b % n == 0:
            return False
    return True