def fix_underscores(args):
    """
    Convert underscores to hyphens in args.

    For example, converts '--gradient_clip' to '--gradient-clip'.

    :param args: iterable, possibly containing args strings with underscores.
    """
    if args:
        new_args = []
        for a in args:
            if type(a) is str and a.startswith('-'):
                a = a.replace('_', '-')
            new_args.append(a)
        args = new_args
    return args