Request.content raises error

[frostming]

Minimal example:

@api.route('/')
async def index(req, resp):
    print(await req.content)
    resp.text = 'Hello world'

When visit index page, error pops:

raceback (most recent call last):
  File "/Users/fming/.local/share/virtualenvs/responder-l5YZbUOR/lib/python3.7/site-packages/uvicorn/protocols/http/h11_impl.py", line 394, in run_asgi
    result = await asgi(self.receive, self.send)
  File "/Users/fming/.local/share/virtualenvs/responder-l5YZbUOR/lib/python3.7/site-packages/uvicorn/middleware/message_logger.py", line 52, in __call__
    await inner(self.receive, self.send)
  File "/Users/fming/wkspace/github/responder/responder/api.py", line 83, in asgi
    resp = await self._dispatch_request(req)
  File "/Users/fming/wkspace/github/responder/responder/api.py", line 114, in _dispatch_request
    await result
  File "test_app.py", line 9, in index
    print(await req.content)
  File "/Users/fming/wkspace/github/responder/responder/models.py", line 133, in content
    return (await self._starlette.body()).encode(self.encoding)
AttributeError: 'bytes' object has no attribute 'encode'

And moreover, there is no encoding attribute in Request object.