class EmptyStackE extends Exception{} public class Stack{ private DoublyLinkedList st; private int size; // TODO: default constructor public Stack(){ } // TODO: Push the element to the top of stack public void push(E elem){ } // TODO: Pop the element off the top of the stack. If nothing to pop, throw EmptyStackE public E pop() throws EmptyStackE { return null; } // TODO: Without affecting the stack, return the element at the top of the stack public E peek() throws IndexOutOfBoundsException{ return null; } public int size() { return this.size; } // TODO: Check if some other object is the same Stack public boolean equals(Object o){ return false; } public String toString(){ return st.toString(); } }