remove unused import and add license info

google/cloud/storage/_experimental/asyncio/async_write_object_stream.py

@@ -1,5 +1,26 @@
-# experimental poc - chandrasiri
-import asyncio
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+NOTE:
+This is _experimental module for upcoming support for Rapid Storage.
+(https://cloud.google.com/blog/products/storage-data-transfer/high-performance-storage-innovations-for-ai-hpc#:~:text=your%20AI%20workloads%3A-,Rapid%20Storage,-%3A%20A%20new)
+
+APIs may not work as intended and are not stable yet. Feature is not
+GA(Generally Available) yet, please contact your TAM(Technical Account Manager)
+if you want to use these Rapid Storage APIs.
+
+"""
 from typing import Optional
 from google.cloud import _storage_v2
 from google.cloud.storage._experimental.asyncio.async_grpc_client import AsyncGrpcClient