code: def readf(prompt, default=None, minval=None, maxval=None,
            allowed_single_chars=None, question_mark=True):
      
  
      return read_value(ftype=float,
                        prompt=prompt,
                        default=default,
                        minval=minval,
                        maxval=maxval,
                        allowed_single_chars=allowed_single_chars,
                        question_mark=question_mark)
docs: Return integer value read from keyboard
  
      Parameters
      ----------
      prompt : str
          Prompt string.
      default : float or None
          Default value.
      minval :  float or None
          Mininum allowed value.
      maxval :  float or None
          Maximum allowed value.
      allowed_single_chars : str
          String containing allowed valid characters.
      question_mark : bool
          If True, display question mark after prompt.
  
      Returns
      -------
      result : float
          Read value.