code: public boolean ordersEqual(OrderBook ob) {
  
      if (ob == null) {
        return false;
      }
  
      Date timestamp = new Date();
      OrderBook thisOb = new OrderBook(timestamp, this.getAsks(), this.getBids());
      OrderBook thatOb = new OrderBook(timestamp, ob.getAsks(), ob.getBids());
      return thisOb.equals(thatOb);
    }
docs: Identical to {@link #equals(Object) equals} method except that this ignores different
  timestamps. In other words, this version of equals returns true if the order internal to the
  OrderBooks are equal but their timestamps are unequal. It returns false if any order between
  the two are different.
  
  @param ob
  @return