Implement a method that checks if a year is a leap year.
All the following rules must be satisfied:
- A year is not a leap year if not divisible by 4
- A year is a leap year if divisible by 4
- A year is a leap year if divisible by 400
- A year is not a leap year if divisible by 100 but not by 400
Examples:
- 1997 is not a leap year (not divisible by 4)
- 1996 is a leap year (divisible by 4)
- 1600 is a leap year (divisible by 400)
- 1800 is not a leap year (divisible by 4, divisible by 100, NOT divisible by 400)
The method should return true if a year is a leap year, and false if it is not.