def euclid_gcd(a, b):  # noqa: WPS111
    """Calculate the greatest common divider using Euclidian algoritm.

    Args:
        a: first number
        b: second number

    Returns:
        the greatest common divider.
    """
    while True:
        remainder = a % b
        if remainder == 0:
            return b
        a, b = b, remainder