堆栈实例没有属性“Something”

Question

stack = Stack()

stack.isEmpty()

它给出了：

  

AttributeError：堆栈实例没有属性'isEmpty'

和

stack.checkBalanceSymbols("SomeString")

给出：

  

AttributeError：堆栈实例没有属性'checkBalancedSymbols'

stack.push(someData)，stack.pop()和stack.peek()正常工作。

from LLNode import Node

class Stack():

    def __init__(self,data):
        self.head = None
        self.data = None

    def push(self,data):
        temp = Node()
        temp.setData(data)
        temp.setNext(self.head)
        self.head = temp

    def pop(self):
        if self.head is None:
            raise IndexError
        else:
            temp = self.head.getData()
            self.head = self.head.getNext()
            return temp

    def peek(self):
        if self.head is None:
            raise IndexError
        else:
            return self.head.getData()

    def isEmpty(self):
        return self.head == None

    def checkBalancedSymbols(self, input):
        symbolsStack = Stack()
        balanced = 0

        for symbol in input:
            if symbol in ["{","[","("]:
                symbolsStack.push(symbol)
            else:
                if symbolsStack.isEmpty():
                    balanced = 0
                    return balanced

                else:
                    topSymbol = symbolsStack.pop()

            if topSymbol != symbol:
                balanced = 0
                return balanced
            else:
                balanced = 1

        return balanced