def _get_omex_description(obj):
    """ Encode the id, name, and description of a model or simulation into an OMEX description

    Args:
        obj (:obj:`Biomodel` or :obj:`Simulation`): object

    Returns:
        :obj:`str`: description
    """
    desc = obj.id
    if obj.name:
        desc += ': ' + obj.name
    if obj.description:
        desc += '\n\n' + obj.description
    return desc
