code: def create_sqs_policy(self, topic_name, topic_arn, topic_subs):
          
          t = self.template
  
          arn_endpoints = []
          url_endpoints = []
          for sub in topic_subs:
              arn_endpoints.append(sub["Endpoint"])
              split_endpoint = sub["Endpoint"].split(":")
              queue_url = "https://%s.%s.amazonaws.com/%s/%s" % (
                  split_endpoint[2],  # literally "sqs"
                  split_endpoint[3],  # AWS region
                  split_endpoint[4],  # AWS ID
                  split_endpoint[5],  # Queue name
              )
              url_endpoints.append(queue_url)
  
          policy_doc = queue_policy(topic_arn, arn_endpoints)
  
          t.add_resource(
              sqs.QueuePolicy(
                  topic_name + "SubPolicy",
                  PolicyDocument=policy_doc,
                  Queues=url_endpoints,
              )
          )
docs: This method creates the SQS policy needed for an SNS subscription. It
          also takes the ARN of the SQS queue and converts it to the URL needed
          for the subscription, as that takes a URL rather than the ARN.