anchor.diff:      NSMutableDictionary(result)[aKeyBlock(i)] := aValueBlock(i);
   end;
   
  +extension method Foundation.INSFastEnumeration.Contains(aItem: id): Boolean;
  +begin
  +  if self is NSArray then
  +    exit (self as NSArray).containsObject(aItem);
  +  for each i in self do begin
  +    if (i = nil) then begin
  +      if (aItem = nil) then exit true;
  +    end
  +    else begin
  +      if i.isEqual(aItem) then exit true;
  +    end;
  +  end;
  +end;
  +
   extension method Foundation.INSFastEnumeration.FirstOrDefault(): nullable id;
   begin
     var lState: NSFastEnumerationState := default(NSFastEnumerationState);
  
positive.code: extension method RemObjects.Elements.System.INSFastEnumeration<T>.Except(aSecond: not nullable Foundation.INSFastEnumeration; aComparator: NSComparator := nil): not nullable RemObjects.Elements.System.INSFastEnumeration<T>; 
  begin
    exit Foundation.INSFastEnumeration(self).Except(aSecond, aComparator);  
  end;
  
  extension method RemObjects.Elements.System.INSFastEnumeration<T>.FirstOrDefault: {nullable} T; 
  
negative.code: extension method Foundation.INSFastEnumeration.Intersect(aSecond: not nullable Foundation.INSFastEnumeration; aComparator: NSComparator := nil): not nullable Foundation.INSFastEnumeration; iterator; public;
  extension method Foundation.INSFastEnumeration.Except(aSecond: not nullable Foundation.INSFastEnumeration; aComparator: NSComparator := nil): not nullable Foundation.INSFastEnumeration; iterator; public;
  
  extension method Foundation.INSFastEnumeration.Contains(aItem: id): Boolean; public;
  extension method Foundation.INSFastEnumeration.FirstOrDefault: nullable id; public;
  extension method Foundation.INSFastEnumeration.FirstOrDefault(aBlock: not nullable PredicateBlock): nullable id; public;
  extension method Foundation.INSFastEnumeration.Count: NSInteger; public;
  