human
Solve the following python programming problem given the following code:
def VerifyReceipt(self, receipt_data, callback) : 
    'Verifies a receipt.  Callback receives a VerifyResponse.' 
    def _OnFetch(response) : 
        response.rethrow () 
        callback (VerifyResponse (receipt_data, response.body)) 
request = { 
        'receipt-data' : base64.b64encode (request), 
        'password' : secrets.GetSecret ('itunes_subscription_secret'), 
} 
    self.http_client.fetch (self._settings ['verify_url'], method = 'POST', body = json.dumps (request), callback = _OnFetch) 

    
    

    Fix the buggy line: 'receipt-data' : base64.b64encode (request) ,
assistant
#Here is Python code to fix the buggy line: 'receipt-data' : base64.

'receipt-data' : base64.b64encode (receipt_data) ,