Python 3

We also were given the stater code

class Node: def __init__(self, value): self.value = value self.next = None def __str__(self): return "Node({})".format(self.value) __repr__ = __str__ class Stack: '''  Creates an empty Stack with support for push and pop operations  >>> x=Stack()  >>> x.pop()  'Stack is empty'  >>> x.push(2)  >>> x.push(4)  >>> x.push(6)  >>> x  Top:Node(6)  Stack:  6  4  2  >>> x.pop()  6  >>> x  Top:Node(4)  Stack:  4  2  >>> len(x)  2  >>> x.peek()  4  '''  def __init__(self): self.top = None def __str__(self): temp=self.top out=[] while temp: out.append(str(temp.value)) temp=temp.next out=' '.join(out) return ('Top:{} Stack: {}'.format(self.top,out)) __repr__=__str__ #Do not edit above this def isEmpty(self): #write your code here def __len__(self): #write your code here def peek(self): #write your code here def push(self,value): #write your code here def pop(self): #write your code here 

[10 pts] In class, we discussed the abstract data structure Stack. A stack is a collection of items where items are added to and removed from the top (LIFO). Use the Node class (an object with a data field and a pointer to the next element) to implement the stack data structure with the following operations: push item) adds a new Node with value-item to the top of the stack. It needs the item and pop0 removes the top Node from the stack. It needs no parameters and returns the value * peek) returns the value of the top Node from the stack but does not remove it. It needs no isEmpty() tests to see whether the stack is empty. It needs no parameters and returns a .len) returns the number of items on the stack. It needs no parameters and returns an integer Stack0 creates a new stack that is empty. It needs no parameters and returns nothing returns nothing. of the Node removed from the stack. Modifies the stack. parameters. The stack is not modified. boolean value (You can add count in the Stack's constructor)