# System.Collections.Generic

``` diff
 namespace System.Collections.Generic {
     public static class CollectionExtensions {
-        public static HashSet.AlternateLookup<TAlternate> GetAlternateLookup<T, TAlternate>(this HashSet<T> @set);
-        public static Dictionary.AlternateLookup<TAlternateKey> GetAlternateLookup<TKey, TValue, TAlternateKey>(this Dictionary<TKey, TValue> dictionary);
-        public static bool TryGetAlternateLookup<T, TAlternate>(this HashSet<T> @set, out HashSet.AlternateLookup<TAlternate> lookup);
-        public static bool TryGetAlternateLookup<TKey, TValue, TAlternateKey>(this Dictionary<TKey, TValue> dictionary, out Dictionary.AlternateLookup<TAlternateKey> lookup);
     }
     public class Dictionary<TKey, TValue> : ICollection, ICollection<KeyValuePair<TKey, TValue>>, IDeserializationCallback, IDictionary, IDictionary<TKey, TValue>, IEnumerable, IEnumerable<KeyValuePair<TKey, TValue>>, IReadOnlyCollection<KeyValuePair<TKey, TValue>>, IReadOnlyDictionary<TKey, TValue>, ISerializable {
+        public Dictionary.AlternateLookup<TAlternateKey> GetAlternateLookup<TAlternateKey>();
+        public bool TryGetAlternateLookup<TAlternateKey>(out Dictionary.AlternateLookup<TAlternateKey> lookup);
     }
     public class HashSet<T> : ICollection<T>, IDeserializationCallback, IEnumerable, IEnumerable<T>, IReadOnlyCollection<T>, IReadOnlySet<T>, ISerializable, ISet<T> {
+        public HashSet.AlternateLookup<TAlternate> GetAlternateLookup<TAlternate>();
+        public bool TryGetAlternateLookup<TAlternate>(out HashSet.AlternateLookup<TAlternate> lookup);
     }
 }
```

