anchor.diff:  
       //
       [<CompiledName("Map")>]
  -    let map (mapping : 'T -> 'U -> 'V) set1 set2 =
  +    let map (mapping : 'T1 -> 'T2 -> 'U) set1 set2 : Set<'U> =
           // Preconditions
           checkNonNull "set1" set1
           checkNonNull "set2" set2
  
positive.code: 
  /// Creates a set given a number of items in the set and a generator function.
  [<CompiledName("Initialize")>]
  let init count (initializer : int -> 'T) =
      // Preconditions
      if count < 0 then
          invalidArg "count" "The number of items cannot be negative."
  
negative.code: 
      //
      [<CompiledName("FoldBack")>]
      let foldBack (folder : 'T -> 'U -> 'State -> 'State) set1 set2 state : 'State =
          // Preconditions
          checkNonNull "set1" set1
          checkNonNull "set2" set2
  