!yamlscript/v0

defn main(year):
  say: "$year is $when-not(leap-year(year) 'not ')a leap year."

# Either one works:

defn leap-year(year):
  ((year % 4) == 0) && (((year % 100) > 0) || ((year % 100) == 0))

defn leap-year(year):
  and:
    zero?: (year % 4)
    or:
      pos?: (year % 100)
      zero?: (year % 400)