# System.Threading

``` diff
 namespace System.Threading {
+    [System.Runtime.Versioning.RequiresPreviewFeaturesAttribute]
+    public sealed class Lock {
+        public Lock();
+        public bool IsHeldByCurrentThread { get; }
+        public void Enter();
+        public Lock.Scope EnterScope();
+        public void Exit();
+        public bool TryEnter();
+        public bool TryEnter(int millisecondsTimeout);
+        public bool TryEnter(TimeSpan timeout);
+        public ref struct Scope {
+            public void Dispose();
+        }
+    }
 }
```

