1 Determines whether the specified day is a leap day.

2 Every four years a leap day helped keep things on track.

3 Determines whether the specified date in the current era is a leap day.

4 DJ in 2002 engaged in industry, Xiaoyu has been the cause with their own deep love of DJ and diligently keep the entrepreneurial spirit of leap day.

5 When overridden in a derived class, determines whether the specified date in the specified era is a leap day.

6 When overridden in a derived class, determines whether a date is a leap day.