         return cocoa.count
 #endif
       }
+    }
+  }
+
+  @inlinable
+  @inline(__always)
+  func contains(_ key: Key) -> Bool {
+    if _fastPath(guaranteedNative) {
+      return asNative.contains(key)
+    }
+    switch self {
+    case .native:
+      return asNative.contains(key)
+#if _runtime(_ObjC)
+    case .cocoa(let cocoa):
+      let cocoaKey = _bridgeAnythingToObjectiveC(key)
+      return cocoa.contains(cocoaKey)
+#endif
     }
   }
 


    @inlinable
    public func _customContainsEquatableElement(_ element: Element) -> Bool? {
      return _variant.index(forKey: element) != nil
    }

    @inlinable


  @inlinable
  @inline(__always)
  internal func contains(_ key: Key) -> Bool {
    return object.object(forKey: key) != nil
  }

  @inlinable
  @inline(__always)
  internal func lookup(_ key: Key) -> Value? {
    return object.object(forKey: key)
  }
