[0q]s0
[1q]s1

[ S. [  l.   4% 0!=0    ## if y %   4:  return 0
        l. 100% 0!=1    ## if y % 100:  return 1
        l. 400% 0!=0    ## if y % 400:  return 0
        1               ##              return 1
     ]x s.L.
]sL                     ## L = isleapYear()

[   Sy
    lyn [ is ]P
    ly lLx
    [not ] 0:y
    [    ] 1:y
    ;yP
    [a leap year]P AP
    OsyLyo
]sT                     ## T = testYear()

1988 lTx
1989 lTx
1900 lTx
2000 lTx