code: def execute_system_command(arg, **_):
      
      usage = "Syntax: system [command].\n"
  
      if not arg:
        return [(None, None, None, usage)]
  
      try:
          command = arg.strip()
          if command.startswith('cd'):
              ok, error_message = handle_cd_command(arg)
              if not ok:
                  return [(None, None, None, error_message)]
              return [(None, None, None, '')]
  
          args = arg.split(' ')
          process = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
          output, error = process.communicate()
          response = output if not error else error
  
          # Python 3 returns bytes. This needs to be decoded to a string.
          if isinstance(response, bytes):
              encoding = locale.getpreferredencoding(False)
              response = response.decode(encoding)
  
          return [(None, None, None, response)]
      except OSError as e:
          return [(None, None, None, 'OSError: %s' % e.strerror)]
docs: Execute a system shell command.