/**
 * Interface for a stack of doubles.
 * @version CSE326b Wi08
 */
interface DStack {
  /** 
   * Test whether this stack is empty.
   * @return true if stack is empty, false if not
   */
  boolean isEmpty();
  
  /**
   * Push a new item on top of this stack.
   * @param d value to be pushed.
   */
  void push(double d);
  
  /**
   * Delete the value that is on top of this stack.
   * @throws EmptyStackException if stack is empty when pop is called.
   */
  void pop();
  
  /**
   * Return the value that is on top of this stack without deleting it.
   * @throws EmptyStackException if stack is empty when top is called.
   */
  double top();
}