private boolean checkValidFeedbackInput(String feedback){
    if (feedback.length() != 2) {
      return false;
    }
    int CL = (Integer)this.state.get(CODELENGTH);
    int b = feedback.charAt(0) - '0';
    int w = feedback.charAt(1) -'0';
    if (!(b <= CL && b >= 0) || !(w <= CL && w >= 0) || !(b+w <=CL && b+w >= 0)){
      return false;
    }
    return true;
  }