code: def create_from_lambda_arn(cls, client, lambda_arn):
          # type: (TypedAWSClient, str) -> LogRetriever
          
          lambda_name = lambda_arn.split(':')[6]
          log_group_name = '/aws/lambda/%s' % lambda_name
          return cls(client, log_group_name)
docs: Create a LogRetriever from a client and lambda arn.
  
          :type client: botocore.client.Logs
          :param client: A ``logs`` client.
  
          :type lambda_arn: str
          :param lambda_arn: The ARN of the lambda function.
  
          :return: An instance of ``LogRetriever``.