Hashtable (A hashtable is a set of elements (unique elements) Each element is identified by its hash value (see Containable) Note: In non-destructive hashtables, elements must not be deleted before they are removed from the table)
Number_Containable (A generic (still abstract) containable that represents any kind of number, by using a template Implementation are given for 'int' and 'float' below)
Queue (A classic FIFO data structure See stack for other methods)