Return the maximum value of all items in {expr}. {expr} can be a list or a dictionary. For a dictionary, it returns the maximum of all values in the dictionary. If {expr} is neither a list nor a dictionary, or one of the items in {expr} cannot be used as a Number this results in an error. An empty |List| or |Dictionary| results in zero. Can also be used as a |method|: mylist->max()