anchor.diff:    }
     
     get balance => _balance;
  -  set balance(double value) {
  +  set balance(num value) {
       if (value.isNegative) {
         throw new Exception('Balance cannot be negative');
       }
  
positive.code:   }
    
    get rate => _rate;
    set rate(double value) {
      if (value.isNegative) {
        throw new Exception('Rate cannot be negative');
      }
  
negative.code:  */
  class Debt {
    var _label;
    num _balance;
    num _rate;
    num _minPayment;
    
    Debt(String label, num balance, num rate, num minPayment) {
      this.label = label;
      this.balance = balance;
      this.rate = rate;
  