asyncio.protocols: fix version availability (#4081)

Co-authored-by: hauntsaninja <>

stdlib/3/asyncio/__init__.pyi

@@ -12,6 +12,8 @@ from asyncio.protocols import (
     DatagramProtocol as DatagramProtocol,
     SubprocessProtocol as SubprocessProtocol,
 )
+if sys.version_info >= (3, 7):
+    from asyncio.protocols import BufferedProtocol as BufferedProtocol
 from asyncio.streams import (
     StreamReader as StreamReader,
     StreamWriter as StreamWriter,

stdlib/3/asyncio/protocols.pyi

@@ -1,3 +1,4 @@
+import sys
 from asyncio import transports
 from typing import Optional, Tuple, Union
 
@@ -11,9 +12,10 @@ class Protocol(BaseProtocol):
     def data_received(self, data: bytes) -> None: ...
     def eof_received(self) -> Optional[bool]: ...
 
-class BufferedProtocol(BaseProtocol):
-    def get_buffer(self, sizehint: int) -> bytearray: ...
-    def buffer_updated(self, nbytes: int) -> None: ...
+if sys.version_info >= (3, 7):
+    class BufferedProtocol(BaseProtocol):
+        def get_buffer(self, sizehint: int) -> bytearray: ...
+        def buffer_updated(self, nbytes: int) -> None: ...
 
 class DatagramProtocol(BaseProtocol):
     def datagram_received(self, data: bytes, addr: Tuple[str, int]) -> None: ...