text: #!/usr/bin/env python3.8
  
  import code
  import os
  import signal
  import sys
  
  def alrm_handler(signum, frame):
      print('Time is up!')
      sys.exit()
  
  signal.signal(signal.SIGALRM, alrm_handler)
  signal.alarm(60)
  
  def handle_input(x):
      line = input(x)
  
      if line.startswith('exit') or line.startswith('quit'):
          sys.exit()
      elif '(' in line or ')' in line:
          return "'We were pretty clear about no parentheses.'"
  
      return line
  
  def main():
      banner = """\
  Welcome to a Python sandbox so safe, it's exposed on the public internet.
  We have one rule and one rule only: no parentheses.
  
  Flag is in /flag and can only be read by executing the /readflag binary.
  """
  
      exit_msg = 'Good-bye!'
  
      class X:
          pass
  
      scope = {
          '__builtins__': {
              'call_me_maybe': os.system,
              'x': X(),
          }
      }
  
      try:
          while True:
              code.interact(banner, handle_input, scope, exit_msg)
      except SystemExit:
          pass
  
      return 0
  
  if __name__ == '__main__':
      sys.exit(main())
  