def METHOD_NAME(region: str = 'us-east'):
    """Returns an IBM COS client object.
      Using process lock to protect not multi process
      safe Boto3.session, which is invoked (default session) by
      boto3.client.
    Args:
        region (str, optional): Client endpoint. Defaults to 'us-east'.
    Returns:
        IBM COS client
    """
    access_key_id, secret_access_key = get_hmac_keys()
    with _get_global_process_lock():
        return ibm_boto3.client(  # type: ignore[union-attr]
            service_name='s3',
            aws_access_key_id=access_key_id,
            aws_secret_access_key=secret_access_key,
            endpoint_url=
            f'https://s3.{region}.cloud-object-storage.appdomain.cloud')