ase file does not exist, the
          data source for the os-release file will be empty.

        * ``distro_release_file`` (string): The path name of the
          `distro release file`_ that is to be used as a data source.

          An empty string (the default) will cause a default search algorithm
          to be used (see `distro release file`_ for details).

          If the specified distro release file does not exist, or if no default
          distro release file can be found, the data source for the distro
          release file will be empty.

        * ``include_name`` (bool): Controls whether uname command output is
          included as a data source. If the uname command is not available in
          the program execution path the data source for the uname command will
          be empty.

        Public instance attributes:

        * ``os_release_file`` (string): The path name of the
          `os-release file`_ that is actually used as a data source. The
          empty string if no distro release file is used as a data source.

        * ``distro_release_file`` (string): The path name of the
          `distro release file`_ that is actually used as a data source. The
          empty string if no distro release file is used as a data source.

        * ``include_lsb`` (bool): The result of the ``include_lsb`` parameter.
          This controls whether the lsb information will be loaded.

        * ``include_uname`` (bool): The result of the ``include_uname``
          parameter. This controls whether the uname information will
          be loaded.

        Raises:

        * :py:exc:`IOError`: Some I/O issue with an os-release file or distro
          release file.

        * :py:exc:`subprocess.CalledProcessError`: The lsb_release command had
          some issue (other than not being available in the program execution
          path).

        * :py:exc:`UnicodeError`: A data source has unexpected characters or
          uses an unexpected encoding.
        r1