code: def get_char(prompt=None):
      
      while True:
          s = get_string(prompt)
          if s is None:
              return None
          if len(s) == 1:
              return s[0]
  
          # Temporarily here for backwards compatibility
          if prompt is None:
              print("Retry: ", end="")
docs: Read a line of text from standard input and return the equivalent char;
      if text is not a single char, user is prompted to retry. If line can't
      be read, return None.