def fill_childgoid2obj(childgoid2obj, parent_obj):
    """Fill childgoid2obj with all child key GO IDs and their objects."""
    for child_obj in parent_obj.children:
        if child_obj.id not in childgoid2obj:
            childgoid2obj[child_obj.id] = child_obj
            fill_childgoid2obj(childgoid2obj, child_obj)
Fill childgoid2obj with all child key GO IDs and their objects.