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

  func index(forKey key: Key) -> Index?
  var count: Int { get }

  func lookup(_ index: Index) -> (key: Key, value: Value)
  func lookup(_ key: Key) -> Value?
}

        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
    }
  }

