Switched implSuper to a symbol

src/TraitBuilder.ts

@@ -4,6 +4,8 @@ import { TraitExpression } from "./TraitExpression"
 import { Extend, StaticMembers } from "./util"
 
 
+declare const implSuperSymbol: unique symbol
+
 type ImplSuper<This> = (
     This extends TraitBuilder<
         any,
@@ -27,7 +29,7 @@ type ImplSuper<This> = (
                     StaticMembers<ImplClass>,
                 ]>
             > &
-            { readonly _tag: "@thilawyn/traitify-ts/Super" }  // TODO: replace with unique symbol?
+            { readonly [implSuperSymbol]: true }
         )
         : never
 )
@@ -94,7 +96,7 @@ export class TraitBuilder<
                 Simplify<
                     Omit<
                         StaticMembers<ImplClassWithAbstract>,
-                        keyof StaticAbstract | "_tag"
+                        keyof StaticAbstract | typeof implSuperSymbol
                     >
                 >
             ),