[Python] Blockchain Project: python code coming up with multiple errors dont know why dont...

please go down to the # Mining a new block section i have highlighted the lines of error

# Module 1 - Create a Blockchain
#importing the Libraries
import datetime
import hashlib
import json
from flask import Flask, jsonify
# Part 01 Building a Blockchain
class Blockchain:
def __init__(self):
self.chain = []
self.create_block(proof = 1, previous_hash ='0' )

def create_block(self, proof, previous_hash):
block ={'index': len(self.chain) +1,
'timestamp': str(datetime.datetime.now()),
'proof': proof,
'previous_hash': previous_hash,}
self.chain.append(block)
return block

def get_previous_block(self):
return self.chain[-1]

def proof_of_work(self, previous_proof):
new_proof = 1
check_proof = False
while check_proof is False:
hash_operation = hashlib.sha256(str(new_proof**2 - previous_proof**2).encode()).hexdigest()
if hash_operation[:4] == '0000':
check_proof = True
else:
new_proof += 1
return new_proof

def hash(self, block):
encoded_block = json.dumps(block, sort_keys = True).encode()
return hashlib.sha256(encoded_block).hexdigest()

def is_chain_valid(self, chain):
previous_block = chain[0]
block_index = 1
while block_index < len(chain):
block = chain[block_index]
if block[previous_hash] != self.hash(previous_block):
return False
previous_proof = previous_block['proof']
proof = block['proof']
hash_operation = hashlib.sha256(str(proof**2 - previous_proof**2).encode()).hexdigest()
if hash_operation[:4] !='0000':
return False
previous_block = block
block_index += 1
return True

# Part 2 - Mining our Blockchain

# creating a Web App
app = Flask(__name__)
app.config['JSONIFY_PRETTYPRINT_REGULAR'] = False
# Creating a Blockchain
blockchain = Blockchain()

# Mining a new block
@app.route('/mine_block', method = ['GET'])

def mine_block():
previous_block = blockchain.get_previous_block()
previous_block = previous_block['proof']
**proof = blockchain.proof_of_work (previous_proof)**
previous_hash = blockchain.hash(previous_block)
blockchain.create_block(proof, previous_hash)
response = {'message' : 'Congratulations, you just mined a block!',
** 'index' : block ['index'],
'timestamp' : block ['timestamp'],
'proof': block ['proof'],
'previous_hash': block ['previous_hash']}**
return jsonify(response), 200

# Getting the Full Blockchain
@app.route('/get_chain', method = ['GET'])
def get_chain():
response = {'chain': blockchain.chain,
'length': len(blockchain.chain)}
return jsonify(response), 200

# Running the app
app.run(host = '0.0.0.0', port = 5000)


I am brand new to this please if anyone can help i would greatly appriciate it

i would like to know where i went wrong and what i can do to fix the issues that came up any advice would be greatly appriciated Thank you in advanced.

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