Client and Service Stubs take 1 request parameter, not one for each field (#311)

README.md

@@ -177,10 +177,10 @@ from grpclib.client import Channel
 async def main():
     channel = Channel(host="127.0.0.1", port=50051)
     service = echo.EchoStub(channel)
-    response = await service.echo(value="hello", extra_times=1)
+    response = await service.echo(echo.EchoRequest(value="hello", extra_times=1))
     print(response)
 
-    async for response in service.echo_stream(value="hello", extra_times=1):
+    async for response in service.echo_stream(echo.EchoRequest(value="hello", extra_times=1)):
         print(response)
 
     # don't forget to close the channel when done!
@@ -206,18 +206,18 @@ service methods:
 
 ```python
 import asyncio
-from echo import EchoBase, EchoResponse, EchoStreamResponse
+from echo import EchoBase, EchoRequest, EchoResponse, EchoStreamResponse
 from grpclib.server import Server
 from typing import AsyncIterator
 
 
 class EchoService(EchoBase):
-    async def echo(self, value: str, extra_times: int) -> "EchoResponse":
-        return EchoResponse([value for _ in range(extra_times)])
+    async def echo(self, echo_request: "EchoRequest") -> "EchoResponse":
+        return EchoResponse([echo_request.value for _ in range(echo_request.extra_times)])
 
-    async def echo_stream(self, value: str, extra_times: int) -> AsyncIterator["EchoStreamResponse"]:
-        for _ in range(extra_times):
-            yield EchoStreamResponse(value)
+    async def echo_stream(self, echo_request: "EchoRequest") -> AsyncIterator["EchoStreamResponse"]:
+        for _ in range(echo_request.extra_times):
+            yield EchoStreamResponse(echo_request.value)
 
 
 async def main():