<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def shlex_process_stdin(process_command, helptext):
 """ Use shlex to process stdin line-by-line. Also prints help text. Requires that @process_command be a Click command object, used for processing single lines of input. helptext is prepended to the standard message printed to interactive sessions. """

    # if input is interactive, print help to stderr
    if sys.stdin.isatty():
        safeprint(
            (
                "{}\n".format(helptext) + "Lines are split with shlex in POSIX mode: "
                "https://docs.python.org/library/shlex.html#parsing-rules\n"
                "Terminate input with Ctrl+D or <EOF>\n"
            ),
            write_to_stderr=True,
        )

    # use readlines() rather than implicit file read line looping to force
    # python to properly capture EOF (otherwise, EOF acts as a flush and
    # things get weird)
    for line in sys.stdin.readlines():
        # get the argument vector:
        # do a shlex split to handle quoted paths with spaces in them
        # also lets us have comments with #
        argv = shlex.split(line, comments=True)
        if argv:
            try:
                process_command.main(args=argv)
            except SystemExit as e:
                if e.code != 0:
                    raise