     var length: Int
 }
 
-class NSMutableString
+class NSMutableString : NSString
 {
-    init(string: String) { length = string.count }
-
-    func character(at: Int) -> unichar { return 0 }
-    func substring(from: Int) -> String { return "" }
-    func substring(to: Int) -> String { return "" }
     func insert(_: String, at: Int) {}
-
-    var length: Int
 }
 
 class NSRange

}

func NSMakeRange(_ loc: Int, _ len: Int) -> NSRange { return NSRange(location: loc, length: len) }

// --- tests ---



typealias unichar = UInt16

class NSObject
{
}

class NSString : NSObject
{
    init(string: String) { length = string.count }

