Added fire property to sub method of state

src/state.ts

@@ -28,9 +28,13 @@ export function createState<T>(initial: T): State<T> {
     subs.forEach((s) => s());
   }
 
-  function sub(fn: Listener) {
+  function sub(fn: Listener, fire = false) {
     subs.push(fn);
 
+    if (fire) {
+      fn();
+    }
+
     return () => {
       const idx = subs.indexOf(fn);
       if (idx > -1) {