anchor.diff:          map.FoldBack (folder, state)
   
       //
  -    [<CompiledName("Choose")>]
  -    let inline choose (chooser : int -> 'T -> 'U option) (map : IntMap<'T>) : IntMap<'U> =
  -        // Preconditions
  -        checkNonNull "map" map
  -
  -        map.Choose chooser
  -
  -    //
  -    [<CompiledName("Filter")>]
  -    let inline filter (predicate : int -> 'T -> bool) (map : IntMap<'T>) : IntMap<'T> =
  -        // Preconditions
  -        checkNonNull "map" map
  -
  -        map.Filter predicate
  -
  -    //
  -    [<CompiledName("Map")>]
  -    let inline map (mapping : int -> 'T -> 'U) (map : IntMap<'T>) : IntMap<'U> =
  -        // Preconditions
  -        checkNonNull "map" map
  -
  -        map.Map mapping
  +    [<CompiledName("Exists")>]
  +    let inline exists (predicate : int -> 'T -> bool) (map : IntMap<'T>) : bool =
  +        // Preconditions
  +        checkNonNull "map" map
  +
  +        map.Exists predicate
  +
  +    //
  +    [<CompiledName("Forall")>]
  +    let inline forall (predicate : int -> 'T -> bool) (map : IntMap<'T>) : bool =
  +        // Preconditions
  +        checkNonNull "map" map
  +
  +        map.Forall predicate
   
       //
       [<CompiledName("Partition")>]
  
positive.code:         /// <inherit />
          member __.Keys
              with get () =
                  notImpl "IDictionary`2.Keys"
  
          /// <inherit />
          member __.Values
              with get () =
                  notImpl "IDictionary`2.Values"
  
          /// <inherit />
  
negative.code:         checkNonNull "map" map
  
          map.Remove key
  
      /// Returns a new IntMap created by merging the two specified IntMaps.
      [<CompiledName("Union")>]
  