Save a generator.

    Parameters
    ----------
    markov : `markovchain.Markov`
        Generator to save.
    fname : `str`
        Output file path.
    args : `argparse.Namespace`
        Command arguments.

def save(markov, fname, args):
    """Save a generator.

    Parameters
    ----------
    markov : `markovchain.Markov`
        Generator to save.
    fname : `str`
        Output file path.
    args : `argparse.Namespace`
        Command arguments.
    """
    if isinstance(markov.storage, JsonStorage):
        if fname is None:
            markov.save(sys.stdout)
        else:
            if fname.endswith('.bz2'):
                open_ = bz2.open
            else:
                open_ = open
            if args.progress:
                print('Saving JSON data...')
            with open_(fname, 'wt') as fp:
                markov.save(fp)
    else:
        markov.save()