code: def s3_stack_push(self, blueprint, force=False):
          
          key_name = stack_template_key_name(blueprint)
          template_url = self.stack_template_url(blueprint)
          try:
              template_exists = self.s3_conn.head_object(
                  Bucket=self.bucket_name, Key=key_name) is not None
          except botocore.exceptions.ClientError as e:
              if e.response['Error']['Code'] == '404':
                  template_exists = False
              else:
                  raise
  
          if template_exists and not force:
              logger.debug("Cloudformation template %s already exists.",
                           template_url)
              return template_url
          self.s3_conn.put_object(Bucket=self.bucket_name,
                                  Key=key_name,
                                  Body=blueprint.rendered,
                                  ServerSideEncryption='AES256',
                                  ACL='bucket-owner-full-control')
          logger.debug("Blueprint %s pushed to %s.", blueprint.name,
                       template_url)
          return template_url
docs: Pushes the rendered blueprint's template to S3.
  
          Verifies that the template doesn't already exist in S3 before
          pushing.
  
          Returns the URL to the template in S3.