let rec integerToBinaryStringHelper i acc =
if i = 0 then
acc
elif i % 2 = 0 then
integerToBinaryStringHelper (i >>> 1) ("0" + acc)
else
integerToBinaryStringHelper (i >>> 1) ("1" + acc)
let integerToBinaryString i =
"0"
integerToBinaryStringHelper i ""
printfn "%s" (integerToBinaryString 10)