====================================================
Add the following method in Day.java
====================================================
	// check if the current object is the end of a month
	public boolean isEndOfAMonth() 
	{
		if (valid(year,month,day+1)) //A smart methd: check whether (year month [day+1]) is still a valid date
			return false;
		else
			return true;
	}
	
====================================================
Add the following method and complete it in Day.java
====================================================
	// create and return a new Day object which is the "next day" of the current day object
	public Day next() 
	{
		if (isEndOfAMonth())
			if (month==12)
				return new Day(year+1,1,1); //Since the current day is the end of the year, the next day should be Jan 01
			else
				return _________________________ // <== your task: first day of next month
		else
			return _________________________ // <== your task: next day of current month
	}


====================================================
Add the following code and complete it in Main.java:

Explanation:
- make use of the .isEndOfAMonth() method of Day
- make use of the .next() method of Day
====================================================
		   if (dayObj.isEndOfAMonth())
			   System.out.println("It is the end of a month.");
		   else
			   System.out.println("It is NOT the end of a month.");
	
		   Day dayObj2 = dayObj.next(); // Here, .next() creates another day object (the next day of dayObj)
		   System.out.println("\nThe next day is " + ___________________); // <== your task: call .toString() for dayObj2