def descendants(term_id, ont_id_to_og, ont_id="17"):
    """
    Get the descendant terms for a given input term.

    Parameters
    ----------
    term_id: The ontology term ID.
    ont_id_to_og: The ontology graph ID map
    ont_id: The ontology ID

    Returns
    ---------
    The term ID's of the descendant terms in the ontology.
    """
    og = ont_id_to_og[ont_id]
    return og.recursive_relationship(
        term_id,
        recurs_relationships=['inv_is_a', 'inv_part_of']
    )