code: def launch(prompt_prefix=None):
      '''Launch a subshell'''
  
      if prompt_prefix:
          os.environ['PROMPT'] = prompt(prompt_prefix)
  
      subprocess.call(cmd(), env=os.environ.dataf launch(prompt_prefix=None):
      '''Launch a subshell'''
  
      if prompt_prefix:
          os.environ['PROMPT'] = prompt(prompt_prefix)
  
      subprocess.call(cmd(), env=os.environ.data)
docs: Launch a subshell