feat(cumulativedeferred): Added subDefer method to CumulativeDeferred

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartpromise',
-  version: '4.1.0',
+  version: '4.2.0',
   description: 'A TypeScript library for managing promises and Deferred constructs, simplifying asynchronous programming.'
 }

ts/smartpromise.classes.cumulativedeferred.ts

@@ -15,6 +15,12 @@ export class CumulativeDeferred {
     }, 0);
   }
 
+  public subDefer() {
+    const done = defer();
+    this.addPromise(done.promise);
+    return done;
+  }
+
   public addPromise(promiseArg: Promise<any>) {
     this.accumulatedPromises.push(promiseArg);
   }