这个模拟代码在链中添加块有什么问题。我认为在while循环中，在计算“mineblock”函数中的散列值之前，nonce值应该递增。否则一旦我们拿到工作成功的证明。我们要分配给块的nonce将比正确的nonce提前一个数字。

import hashlib

class Block:
    def __init__(self, no, nonce, data, hashcode, prev):
        self.no=no
        self.nonce=nonce
        self.data=data
        self.hashcode=hash
        self.prev=prev

    def getStringVal():
        return self.no, self.nonce, self.data, self.hashcode, self.prev

class Blockchain:
    def __init__(self):
        self.chain=[]
        self.prefix="0000"

    def addNewBlock(self, data):
        no=len(self.chain)
        nonce=0

        if len(self.chain)==0:
            prev="0"
        else:
            prev=self.chain[-1].hashcode

        myHash hashlib.sha256(str(data).encode('utf-8')).hexdigest()
        block=Block(no, nonce, data, myHash, prev)

        self.chain.append(block)

    def printBlockchain(self):
        chainDict={}
        for no in range(len(self.chain)):
            chainDict[no]=self.chain[no].getStringVal()
        print(chainDict)

    def mineChain(self):
        brokenLink=self.checkIfBroken

        if (brokenLink==None):
            pass
        else:
            for block in self.chain[brokenLink.no:]:
                print("Mining Block:" block.getStringVal())
                self.mineBlock(block)

    def mineBlock(self, block):
        nonce=0
        myHash=hashlib.sha256(str(nonce)+str(block.data)).encode('utf-8').hexdigest()
        while myHash[0:4]!=self.prefix:
            myHash=hashlib.sha256(str(nonce)+str(block.data)).encode('utf-8').hexdigest()
            nonce=nonce+1
        else:
            self.chain[block.no].hashcode=myHash
            self.chain[block.no].nonce=nonce
            if (block.no<len(self.chain)-1:
                self.chain[block.no+1].prev=myHash

    def checkIfBroken(self):
        for no in range(len(self.chain)):
            if (self.chain[no].hashcode[0:4]==self.prefix):
                pass
            else self.chain[no]

    def changeData(self, no, data):
        self.chain[no].data=data
        self.chain.[no].hashcode=myHash=hashlib.sha256(str(nonce)+str(block.data)).encode('utf-8').hexdigest()`enter code here`