Ask user to input a data in the form YYYY and check if it is a leap year. If it is, print leap year, if not then output it is not a leap year.

def check_leap_year(year):
  if year % 4 == 0:
    if year % 100 == 0:
      if year % 400 == 0:
        return 'leap year'
      return 'not a leap year'
    return 'leap year'
  return 'not a leap year'

print(check_leap_year(2000))