code: async def read(self) -> bytes:
          
          if self._read_bytes is None:
              body = bytearray()
              while True:
                  chunk = await self._payload.readany()
                  body.extend(chunk)
                  if self._client_max_size:
                      body_size = len(body)
                      if body_size >= self._client_max_size:
                          raise HTTPRequestEntityTooLarge(
                              max_size=self._client_max_size,
                              actual_size=body_size
                          )
                  if not chunk:
                      break
              self._read_bytes = bytes(body)
          return self._read_bytes
docs: Read request body if present.
  
          Returns bytes object with full request content.