anchor.diff:                  // logically should never hit here
                   failwithumf ()
   
  +        // clashing
           else
               
               // handle clash cases
  
positive.code: 
              | Singlet hkv' ->
                  
                  // additional entry; convert Singlet to Multiple
                  let idx = hashToIndex hkv.H dep
                  let idx' = hashToIndex hkv'.H dep
                  if idx <> idx' then
  
negative.code: open System
  open Prime
  
  /// Hash, key, value triple in a struct for efficiency.
  type internal Hkv<'k, 'v when 'k : comparison> =
      struct
          new (h, k, v) = { H = h; K = k; V = v }
          val H : int
          val K : 'k
          val V : 'v
  