def paths(bot, nb_name):
    """Returns the paths of notebook to execute and to write."""
    nb_dir = bot.config.papermill.nb_dir #Notebook directory (from config)
    nb_dir = nb_dir if nb_dir.endswith('/') else nb_dir+'/' #append '/' if missing
    path_in = nb_dir + nb_name
    path_out = nb_dir + bot.config.papermill.prefix + nb_name
    return(path_in, path_out)