Data Structures
•Doubly Linked list...
• private: (each node has a node * prev)
• node * head;
• node * tail;  //???helpful?
•Again, there is nothing in a stack that will benefit from each node having a pointer to the previous node.
•Using a doubly linked list to allow the “top” to be at the “end” or tail position, this is a poor choice...wastes memory and adds additional operations...
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