How to use the pysubs2.ssafile.SSAFile.from_file function in pysubs2

os.makedirs(args.output_dir)

        if args.output_enc is None:
            args.output_enc = args.input_enc

        if args.files:
            for path in args.files:
                if not op.exists(path):
                    print("Skipping", path, "(does not exist)")
                    errors += 1
                elif not op.isfile(path):
                    print("Skipping", path, "(not a file)")
                    errors += 1
                else:
                    with open(path, encoding=args.input_enc) as infile:
                        subs = SSAFile.from_file(infile, args.input_format, args.fps)

                    self.process(subs, args)

                    if args.output_format is None:
                        outpath = path
                        output_format = subs.format
                    else:
                        ext = get_file_extension(args.output_format)
                        outpath = change_ext(path, ext)
                        output_format = args.output_format

                    if args.output_dir is not None:
                        _, filename = op.split(outpath)
                        outpath = op.join(args.output_dir, filename)

                    with open(outpath, "w", encoding=args.output_enc) as outfile:

if args.output_dir is not None:
                        _, filename = op.split(outpath)
                        outpath = op.join(args.output_dir, filename)

                    with open(outpath, "w", encoding=args.output_enc) as outfile:
                        subs.to_file(outfile, output_format, args.fps)
        else:
            if PY3:
                infile = io.TextIOWrapper(sys.stdin.buffer, args.input_enc)
                outfile = io.TextIOWrapper(sys.stdout.buffer, args.output_enc)
            else:
                infile = io.TextIOWrapper(sys.stdin, args.input_enc)
                outfile = io.TextIOWrapper(sys.stdout, args.output_enc)

            subs = SSAFile.from_file(infile, args.input_format, args.fps)
            self.process(subs, args)
            output_format = args.output_format or subs.format
            subs.to_file(outfile, output_format, args.fps)

        return (0 if errors == 0 else 1)