Update the documentation notebook of a given module.

def update_module_page(mod, dest_path='.'):
    "Update the documentation notebook of a given module."
    doc_path = get_doc_path(mod, dest_path)
    strip_name = strip_fastai(mod.__name__)
    nb = read_nb(doc_path)
    cells = nb['cells']

    link_markdown_cells(cells, get_imported_modules(cells, mod.__name__))

    type_dict = read_nb_types(cells)
    gvar_map = get_global_vars(mod)
    for name in get_exports(mod):
        if name not in gvar_map: continue
        code = gvar_map[name]
        if name in type_dict: cells[type_dict[name]] = get_md_cell(code)
        else: cells.append(get_md_cell(code))

    pos_dict = read_nb_content(cells, strip_name)
    ft_names = get_ft_names(mod, include_inner=True)
    new_fts = list(set(ft_names) - set(pos_dict.keys()))
    if new_fts: print(f'Found new fuctions for {mod}. Please document:\n{new_fts}')
    existing, undoc_cells, new_cells = parse_sections(cells)
    for ft_name in new_fts: new_cells.extend([get_doc_cell(ft_name), get_empty_cell()])
    if len(new_cells) > 1: nb['cells'] = existing + undoc_cells + new_cells

    write_nb(nb, doc_path)
    return doc_path