Write ``env`` as a varint-size-prefixed protobuf frame.
(writer: asyncio.StreamWriter, env: pb.Envelope)
| 78 | self._reader_task: asyncio.Task[None] | None = None |
| 79 | self._stderr_task: asyncio.Task[None] | None = None |
| 80 | self._pending: dict[int, _UnaryPending | _StreamPending] = {} |
| 81 | self._next_id = 1 |
| 82 | self._closed = False |
| 83 | self._start_lock = asyncio.Lock() |
| 84 | |
| 85 | async def _ensure_started(self) -> None: |
| 86 | if self._process is not None: |
| 87 | return |