def dict_to_desc(d: dict):
    """
    Transform dictionary into a text-based description.

    Parameters
    ----------
    d : dict
        Mapping factors->indicators.

    Returns
    -------
    desc : str
        Text-form description of the model.

    """
    desc = str()
    for lat, inds in d.items():
        if lat != -1:
            inds = ' + '.join(inds)
            desc += f'{lat} =~ {inds}\n'
    return desc