SyntaxError: '(' was never closed

 public_key = base64.b64decode(public_key).hex() 
signature = base64.b64decode(signature) 

 from enum import verify  
import hashlib  
import time  
import base64  
import ecdsa  
from flask import Flask, request  
 
class Block:  
    def __init__(self, index, timestamp, data, previous_hash):  
        self.index = index  
        self.timestamp = timestamp  
        self.data = data  
        self.previous_hash = previous_hash  
        self.hash = self.hash_block()  
 
    def hash_block(self):  
        sha = hashlib.sha256()  
        sha.update((str(self.index) + str(self.timestamp) + str(self.data) + str(self.previous_hash)).encode('utf-8'))  
        return sha.hexdigest()  
 
    @staticmethod 
    def validate_signature(public_key, signature, message):  
        public_key = base64.b64decode(public_key).hex()  
        signature = base64.b64decode(signature) 
        verif_key = ecdsa.VerifyingKey.from_string(bytes.fromhex(public_key), curve=ecdsa.SECP256k1)  
        try:  
            return verif_key.verify(signature, message.encode())  
        except Exception as e:  
            return False