Add example script

Author: taras

eager_future.py

@@ -0,0 +1,42 @@
+from functools import partial, Placeholder as _
+
+import asyncio
+
+print(asyncio.Future)  # Will show if it's the C or Python version
+print(asyncio.Task)
+
+def callback_no_exc(fut, idx):
+    print(f"callback_no_throw: {idx}")
+
+
+def callback_with_exc(fut):
+    print("callback_with_exception")
+    raise RuntimeError("TEST EXCEPTION")
+
+
+async def func(fut):
+    try:
+        print("func: entered")
+        await fut
+        print("func: done")
+    except Exception as exc:
+        print(f"func: EXCEPTION: {exc}")
+
+
+async def main():
+    loop = asyncio.get_running_loop()
+    loop.set_task_factory(asyncio.eager_task_factory)
+    fut = asyncio.Future(loop=loop)
+    fut.add_done_callback(partial(callback_no_exc, _, 1))
+    fut.add_done_callback(callback_with_exc)
+    fut.add_done_callback(partial(callback_no_exc, _, 2))
+    loop.create_task(func(fut))
+    await asyncio.sleep(1)
+    print("main: before set_result")
+    fut.eager_set_result(None)
+    print("main: set_result done")
+    await asyncio.sleep(1)
+    print("main: done")
+
+
+asyncio.run(main())