CollectionExtensions

Available Extensions
AddRange
Clone
AddIfNotExists
UpdateValue
DeleteIfExists
AreValuesNull

Example

collection.AddRange(items);

//

var dupcollection = collection.Clone();

//

collection.AddIfNotExists(item);

//

collection.UpdateValue(item, newItem);

//

collection.DeleteIfExists(item);

//

bool areNull = collection.AreValuesNull();

Demo

you can run demo and see this feature.