def compss_open(file_name, mode='r'):
    # type: (str, str) -> object
    """ Dummy compss_open.

    Open the given file with the defined mode (see builtin open).

    :param file_name: The file name to open.
    :param mode: Open mode. Options = [w, r+ or a , r or empty]. Default=r.
    :return: An object of 'file' type.
    :raise IOError: If the file can not be opened.
    """
    return open(file_name, mode)