def leapdays(y1, y2):
    y1 -= 1
    y2 -= 1
    return (y2//4 - y1//4) - (y2//100 - y1//100) + (y2//400 - y1//400)
annotate windows.
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/python/Lib/calendar.py/leapdays--crossover with--dataset/ETHPy150Open CGATOxford/cgat/scripts/gff2table.py/annotateWindows