code: public CyclicYear roll(int amount) {
  
          if (amount == 0) {
              return this;
          }
  
          return CyclicYear.of(MathUtils.floorModulo(MathUtils.safeAdd(this.year - 1, amount), 60) + 1);
  
      }
docs: /*[deutsch]
  <p>Rollt dieses zyklische Jahr um den angegebenen Betrag. </p>
  
  @param   amount  determines how many years/units this instance should be rolled
  @return  changed copy of this instance