   /// Returns a new string made by replacing in the `String`
   /// all percent escapes with the matching characters as determined
   /// by a given encoding.
-  @available(*, deprecated, message: "Use removingPercentEncoding instead, which always uses the recommended UTF-8 encoding.")
+  @available(swift, deprecated: 3.2, obsoleted: 4.0,
+    message: "Use removingPercentEncoding instead, which always uses the recommended UTF-8 encoding.")
   public func replacingPercentEscapes(
     using encoding: String.Encoding
   ) -> String? {

  }
}

extension StringProtocol {
  // - (const char *)fileSystemRepresentation


  /// the `String` characters contained in a given character set.
  public func trimmingCharacters(in set: CharacterSet) -> String {
    return _ns.trimmingCharacters(in: set)
  }

  // @property (readonly, copy) NSString *localizedUppercaseString NS_AVAILABLE(10_11, 9_0);
