anchor.diff:              // If it is negative, its bitwise complement signifies the next nearest element to be found.
               | x -> ~~~ x
           match Array.tryItem idx arr with
  -        | Some(RangeInclusive (k1, k2, x)) when k1 <= k && k <= k2 -> Some x
  -        | Some(Singleton(k1, x)) when k1 = k -> Some x
  +        | Some((k1, k2, x)) when smallerOrEqual k1 k && smallerOrEqual k k2 -> Some x
           | None | Some _ -> None
   
       [<CompiledName("ContainsKey")>]
  
positive.code:     let tryFind k (RangeMap arr) =
          let idx =
              // .NET's binary search function returns special integer values depending on the outcome.
              match Array.BinarySearch(arr, Singleton (k, Unchecked.defaultof<_>)) with
              // If it is positive, then an exact element was found in the array.
              | x when x >= 0 -> x
              // If it is the bitwise complement of the array's length, the requested element
  
negative.code:         let mapKeys (keys, value) =
              keys
              |> Array.map (fun (x1, x2) ->
                  if smallerOrEqual x1 x2 then
                      (x1, x2, value)
                  else
                      (x2, x1, value)
              )
          Array.collect mapKeys pairs |> consistencyCheck
  