) -> TypeModelSet:
    known_models = known_models or set()
    fields = get_model_fields(model)
    get_flat_models_from_fields(fields, known_models=known_models)
    return known_models


def get_flat_models_from_annotation(
    annotation: Any, known_models: TypeModelSet
) -> TypeModelSet:
    origin = get_origin(annotation)
    if origin is not None:
        for arg in get_args(annotation):