// Minimal setup for coding katas (I usually put this in "setup.fsx")
let __<'T> : 'T = failwith "Placeholder '__' was not filled!"
let shouldEqual a b = 
  if not (a = b) then 
    failwithf "Values are not equal!\n  Expected: %A\n  Received: %A" a b

// Sample tasks with placeholders and equality tests (#loads "setup.fsx")
let nums = 40 + __
shouldEqual nums 42