// ComicBookCharacterDefault.ts

"use strict";

class ComicBookCharacterDefault {
  constructor(
    public alias: string,
    public health: number,
    public strength: number,
    protected secretIdentity: string
  ) {}
}

export { ComicBookCharacterDefault };

// ComicBookCharacterDefault.ts

"use strict";

class ComicBookCharacterDefault {
  constructor(
    public alias: string,
    public health: number,
    public strength: number,
    private secretIdentity: string
  ) {}
}

export { ComicBookCharacterDefault };

--- 
+++ 
@@ -7,7 +7,7 @@
     public alias: string,
     public health: number,
     public strength: number,
-    private secretIdentity: string
+    protected secretIdentity: string
   ) {}
 }
 
Change access level for secretIdentity
