bpo-34666: Implement stream.awrite() and stream.aclose() (GH-9274)

diff --git a/Lib/asyncio/streams.py b/Lib/asyncio/streams.py
index e7fb22e..0afc66a 100644
--- a/Lib/asyncio/streams.py
+++ b/Lib/asyncio/streams.py
@@ -348,7 +348,7 @@
         # a reader can be garbage collected
         # after connection closing
         self._protocol._untrack_reader()
-        return self._transport.close()
+        self._transport.close()
 
     def is_closing(self):
         return self._transport.is_closing()
@@ -381,6 +381,14 @@
             await sleep(0, loop=self._loop)
         await self._protocol._drain_helper()
 
+    async def aclose(self):
+        self.close()
+        await self.wait_closed()
+
+    async def awrite(self, data):
+        self.write(data)
+        await self.drain()
+
 
 class StreamReader: