feat(utils): adds isCancelled

src/index.ts

@@ -1 +1,2 @@
 export * from './definitions';
+export * from './utils';

src/utils/index.ts

@@ -0,0 +1 @@
+export * from './is-cancelled';

src/utils/is-cancelled.ts

@@ -0,0 +1,13 @@
+import { Context } from '../definitions';
+
+/**
+ * A promise returning function that will
+ * resolve with `true` if `context.cancellation`
+ * has finalized, and `false` otherwise.
+ */
+export async function isCancelled(context: Context): Promise<boolean> {
+  return new Promise<boolean>((resolve) => {
+    context.cancellation.finally(() => resolve(true));
+    setTimeout(() => resolve(false), 0);
+  });
+}