Removes all items from the container and returns nil.
| empty! < abstract-bag/set-container > |
| empty! < abstract-queue > |
| empty! < alist-container > |
| empty! < cl-graph:basic-graph > |
| empty! < basic-queue > |
| empty! < binary-search-tree > |
| empty! < contents-as-array-mixin > |
| empty! < contents-as-hashtable-mixin > |
| empty! < contents-as-list-mixin > |
| empty! < dlist-container > |
| empty! :after < cl-graph:graph-container > |
| empty! < hash-table > |
| empty! < priority-queue-on-container > |
| empty! < quad-tree > |
| empty! < ring-buffer > |
| empty! < stable-associative-container > |
| empty! < stack-container > |