fix(core): update

ts/index.ts

@@ -1,4 +1,7 @@
-export const filter = async<T>(arrayArg: T[], filterFunction: (itemArg: T) => Promise<boolean>): Promise<T[]> => {
+export const filter = async <T>(
+  arrayArg: T[],
+  filterFunction: (itemArg: T) => Promise<boolean>
+): Promise<T[]> => {
   const returnArray: T[] = [];
   for (const itemArg of arrayArg) {
     const filterResult = await filterFunction(itemArg);
@@ -7,4 +10,22 @@ export const filter = async<T>(arrayArg: T[], filterFunction: (itemArg: T) => Pr
     }
   }
   return returnArray;
-}
+};
+
+export const deduplicate = async <T, K>(
+  arrayArg: T[],
+  keyCreation: (itemArg: T) => Promise<K>
+): Promise<T[]> => {
+  const keysSet: Set<K> = new Set();
+  const returnArray: T[] = [];
+
+  for (const itemArg of arrayArg) {
+    const key = await keyCreation(itemArg);
+    if (!keysSet.has(key)) {
+      keysSet.add(key);
+      returnArray.push(itemArg);
+    }
+  }
+
+  return returnArray;
+};