diff --git a/src/utils/set.ts b/src/utils/set.ts
index 8c201cb..6638cf2 100644
--- a/src/utils/set.ts
+++ b/src/utils/set.ts
@@ -51,3 +51,4 @@ export function union<A>(a: Set<A>, b: Set<A>): Set<A> {
   }
   return result
 }
+