Removes (and returns) the first item in an ordered
container.
Behavior is undefined if the container is empty.
| delete-first :before < abstract-queue > |
| delete-first < basic-queue > |
| delete-first < list-container > |
| delete-first < priority-queue-on-container > |
| delete-first < ring-buffer > |
| delete-first < sorted-list-container > |
| delete-first < vector-container > |