<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def launch():
 """Ensure that python is running from the Lore virtualenv past this point. """

    if launched():
        check_version()
        os.chdir(ROOT)
        return

    if not os.path.exists(BIN_LORE):
        missing = ' %s virtualenv is missing.' % APP
        if '--launched' in sys.argv:
            sys.exit(ansi.error() + missing + ' Please check for errors during:\n $ lore install\n')
        else:
            print(ansi.warning() + missing)
            import lore.__main__
            lore.__main__.install(None, None)

    reboot('--env-launched')