TypeError: must be str, not bytes

[Zhsv]

Thank you very much.
Yes, the code I tried and did something when there were mistakes. Now it seems to have received a response from the server, but not the kind who waited

---

import urllib
from urllib.request import urlopen
import json
import time
import hmac,hashlib
import random
import base64

	
class cryptopia:
        def __init__(self, key='', secret='', url='https://www.cryptopia.co.nz/api/'):
                self.apikey = key
                self.apisecret = secret
                self.apisite = url
                self.api_params = {}
                return
        def public_api(self, meth):
                return json.loads(urlopen(urlopen(self.apisite + meth)).read())
        def private_api(self, method, values={}, req={}):
                time.sleep(1)
                if method in self.private:
                        url = "https://www.cryptopia.co.nz/Api/" + method
                        nonce = str(int(time.time()))
                        requestContentBase64String = base64.b64encode(hashlib.md5(json.dumps(values)).digest())
                        signature = self.key + "POST" + urllib.quote_plus(url).lower() + nonce + requestContentBase64String
                        hmacsignature = base64.b64encode(hmac.new(base64.b64decode(self.secret), signature, hashlib.sha256).digest())
                        header_value = "amx " + self.key + ":" + hmacsignature + ":" + nonce
                        headers = { 'Authorization': header_value }
                        r = requests.post(url, json = values, headers=headers)
                elif method in self.public:
                        url = 'https://www.cryptopia.co.nz/api/' + method 
                        r = requests.get(url, params=values) 
                else:
                        return 'Call Not Identified - Something Went Wrong.'
                response = r.content
                print ("( Response ): " + response)
                return response.replace("false","False").replace("true","True").replace('":null','":None' )
        def getCurrencies(self):
                return self.public_api('GetCurrencies')
        def getTradePairs(self):
                return self.public_api('GetTradePairs')
        def getBalances(self):
                return self.private_api('GetBalance')
	
		
API_KEY = 'ac85417173...abdf98138e...02'
API_SECRET = 'KY9R6bgPfQeDr2kV...rwm4aoGk0EvQwU...eduafbsk'

my_api = cryptopia(API_KEY, API_SECRET)

# test public api call
#print (my_api.getMarketOrders)

# test private api call
print (my_api.getBalances)

response

<bound method cryptopia.getBalances of <__main__.cryptopia object at 0x0205E0B0>>
>>>