def biggest(a, b):
    """
        This function returns the biggest of the numbers (but it does checks for None).

        Input:
            a: int, first number;
            b: int, second number.

        Output:
            biggest: int, the biggest number of the passed numbers (the non-None number, if one of the number was None,
                and None, if both numbers were None).
    """

    if a is None:
        return b
    if b is None or a > b:
        return a
    else:
        return b