How to use the argcomplete.ensure_str function in argcomplete

output_stream = os.fdopen(8, "wb")
    ifs = os.environ.get("_ARGCOMPLETE_IFS", "\v")
    if len(ifs) != 1:
        sys.exit(1)
    current = os.environ["COMP_CUR"]
    prev = os.environ["COMP_PREV"]
    comp_line = os.environ["COMP_LINE"]
    comp_point = int(os.environ["COMP_POINT"])

    # Adjust comp_point for wide chars
    if USING_PYTHON2:
        comp_point = len(comp_line[:comp_point].decode(SYS_ENCODING))
    else:
        comp_point = len(comp_line.encode(SYS_ENCODING)[:comp_point].decode(SYS_ENCODING))

    comp_line = ensure_str(comp_line)
    comp_words = split_line(comp_line, comp_point)[3]
    if "COMP_CWORD" in os.environ and os.environ["COMP_CWORD"] == "1":
        keys = [x for x in list(COMMAND_MAPPINGS.keys()) if x.startswith(current)]
        output_stream.write(ifs.join(keys).encode(SYS_ENCODING))
        output_stream.flush()
        sys.exit(0)
    else:
        command = prev
        if len(comp_words) > 1:
            command = comp_words[1]
        if command not in COMMAND_MAPPINGS:
            sys.exit(1)
        command_type = COMMAND_MAPPINGS[command]
        if command_type == "shell":
            command = command + ".sh"
        if command_type == "ndtshell":

if output_stream is None:
                try:
                    output_stream = os.fdopen(8, "wb")
                except IOError:
                    argcomplete.debug("Unable to open fd 8 for writing, quitting")
                    exit_method(1)

            ifs = os.environ.get("_ARGCOMPLETE_IFS", "\013")
            if len(ifs) != 1:
                argcomplete.debug("Invalid value for IFS, quitting [{v}]".format(v=ifs))
                exit_method(1)

            comp_line = os.environ["COMP_LINE"]
            comp_point = int(os.environ["COMP_POINT"])

            comp_line = argcomplete.ensure_str(comp_line)

            ##############################
            # SWAPPED FOR AUTOCOMPLETER
            #
            # Replaced with our own tokenizer function
            ##############################
            tokens, _, begidx, endidx = tokens_for_completion(comp_line, comp_point)

            # _ARGCOMPLETE is set by the shell script to tell us where comp_words
            # should start, based on what we're completing.
            # 1: