code: def string(prompt=None, empty=False):
      
      s = _prompt_input(prompt)
      if empty and not s:
          return None
      else:
          if s:
              return s
          else:
              return string(prompt=prompt, empty=empty)
docs: Prompt a string.
  
      Parameters
      ----------
      prompt : str, optional
          Use an alternative prompt.
      empty : bool, optional
          Allow an empty response.
  
      Returns
      -------
      str or None
          A str if the user entered a non-empty string.
          None if the user pressed only Enter and ``empty`` was True.