from [this post](https://forum.nim-lang.org/t/3257/2)
convert something like the following to suit your specific usage
var
LoopSz = faces.len
res: array[LoopSz, int]
parallel:
for i in 0..LoopSz-1:
spawn whateverNeedsDoingInParallel(..., res[i], ....)
sync()
for i in 0..LoopSz-1:
aggResult = doSomeAggregationOfResults(res[i])
Note: currently don't do `0..<LoopSz` (unless that has been fixed).
