code: def to_cloudformation(self, **kwargs):
          
          function = kwargs.get('function')
  
          if not function:
              raise TypeError("Missing required keyword argument: function")
  
          source_arn = self.get_source_arn()
          permission = self._construct_permission(function, source_arn=source_arn)
          subscription_filter = self.get_subscription_filter(function, permission)
          resources = [permission, subscription_filter]
  
          return resources
docs: Returns the CloudWatch Logs Subscription Filter and Lambda Permission to which this CloudWatch Logs event source
          corresponds.
  
          :param dict kwargs: no existing resources need to be modified
          :returns: a list of vanilla CloudFormation Resources, to which this push event expands
          :rtype: list