examples: add async_coroutines

examples/async_coroutines.py

@@ -0,0 +1,37 @@
+"""
+Asynchronous examples using `asyncio`, `async` and `await` on `python>=3.7`.
+"""
+import asyncio
+from tqdm.asyncio import tqdm, trange
+
+
+def count(start=0, step=1):
+    i = start
+    while True:
+        new_start = yield i
+        if new_start is None:
+            i += step
+        else:
+            i = new_start
+
+
+async def main():
+    N = int(1e6)
+    async for row in tqdm(trange(N, desc="inner"), desc="outer"):
+        if row >= N:
+            break
+    with tqdm(count(), desc="coroutine", total=N + 2) as pbar:
+        async for row in pbar:
+            if row == N:
+                pbar.send(-10)
+            elif row < 0:
+                assert row == -9
+                break
+    # should be under 10 seconds
+    for i in tqdm.as_completed(list(map(asyncio.sleep, [1] * 10)),
+                               desc="as_completed"):
+        await i
+
+
+if __name__ == "__main__":
+    asyncio.run(main())