# Returns the maximum value of a nonempty sequence
# of elements that can be compared with the <-operator.
def myMax(seq):
    if len(seq) == 0:
        raise ValueError("seq is empty")
    max = seq[0]
    for x in seq:
        if max < x:
            max = x
    return max

def main():
    print(max([1, 2, 3]))
    print(max([3, 2, 1]))
    print(max(("a", "b")))
    print(max([]))
main()