Re: A path commonPrefix function

[e]

In `rangeAt` you have 
    
    
    if xs[result.minAt] < xs[i]: result.minAt = i
    if xs[result.minAt] > xs[i]: result.minAt = i
    
    
    Run

whereas I suspect you meant to use `maxAt` in the second line. Does this affect 
your timing results?