Leap

Given a year, report if it is a leap year.

The tricky thing here is that a leap year in the Gregorian calendar occurs:

on every year that is evenly divisible by 4
  except every year that is evenly divisible by 100
    unless the year is also evenly divisible by 400

For example, 1997 is not a leap year, but 1996 is. 1900 is not a leap
year, but 2000 is.

Notes

Though our exercise adopts some very simple rules, there is more to
learn!

For a delightful, four minute explanation of the whole leap year
phenomenon, go watch this youtube video.