pythonでのmaxの使い方

max
max(...)

max(iterable, *[, default=obj, key=func]) -> value
max(arg1, arg2, *args, *[, key=func]) -> value

With a single iterable argument, return its biggest item. The
default keyword-only argument specifies an object to return if
the provided iterable is empty.
With two or more arguments, return the largest argument.

1:

>>> max(1,2,3,4,5)
5

2:

>>> max([1,2,3],[4],[5,6],key=lambda x:len(x))
[1, 2, 3]

3:

>>> max([],default="empty")
'empty'