checks whether a collection contains any items
The following invariant should always hold:
std::is_empty(collection) == (std::length_of(collection) == 0)
| std::is_not_empty | checks whether a collection contains at least one item |
| std::length_of | returns the number of items within a collection |
| std_types::io | checks if the input-output object contains any event registrations |
| std_types::list | returns whether the list is empty or not |
| std_types::octet_string | returns whether the octet string is empty or not |
| std_types::quad_octet_string | returns whether the quad-octet string is empty or not |