WP determine the topmost parent of a term

WP-Top-Most-Taxonomy

function get_term_top_most_parent($term_id, $taxonomy){
    // start from the current term
    $parent  = get_term_by( 'id', $term_id, $taxonomy);
    // climb up the hierarchy until we reach a term with parent = '0'
    while ($parent->parent != '0'){
        $term_id = $parent->parent;

        $parent  = get_term_by( 'id', $term_id, $taxonomy);
    }
    return $parent;
}