code: def get_float(prompt=None):
      
      while True:
          s = get_string(prompt)
          if s is None:
              return None
          if len(s) > 0 and re.search(r"^[+-]?\d*(?:\.\d*)?$", s):
              try:
                  return float(s)
              except ValueError:
                  pass
  
          # 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 float
      as precisely as possible; if text does not represent a double, user is
      prompted to retry. If line can't be read, return None.