added unit testing, and started implementing unit tests...phew

node_modules/mimic-fn/index.d.ts

@@ -0,0 +1,15 @@
+/**
+ * Make a function mimic another one. It will copy over the properties `name`, `length`, `displayName`, and any custom properties you may have set.
+ *
+ * @param to - Mimicking function.
+ * @param from - Function to mimic.
+ * @returns The modified `to` function.
+ */
+export default function mimicFn<
+	ArgumentsType extends unknown[],
+	ReturnType,
+	FunctionType extends (...arguments: ArgumentsType) => ReturnType
+>(
+	to: (...arguments: ArgumentsType) => ReturnType,
+	from: FunctionType
+): FunctionType;