text: import ssl
  import typing
  
  import anyio
  
  from .._exceptions import (
      ConnectError,
      ConnectTimeout,
      ReadError,
      ReadTimeout,
      WriteError,
      WriteTimeout,
      map_exceptions,
  )
  from .._utils import is_socket_readable
  from .base import AsyncNetworkBackend, AsyncNetworkStream
  
  
  class AsyncIOStream(AsyncNetworkStream):
      def __init__(self, stream: anyio.abc.ByteStream) -> None:
          self._stream = stream
  
      async def read(self, max_bytes: int, timeout: float = None) -> bytes:
          exc_map = {
              TimeoutError: ReadTimeout,
              anyio.BrokenResourceError: ReadError,
          }
          with map_exceptions(exc_map):
              with anyio.fail_after(timeout):
                  try:
                      return await self._stream.receive(max_bytes=max_bytes)
                  except anyio.EndOfStream:  # pragma: nocover
                      return b""
  
      async def write(self, buffer: bytes, timeout: float = None) -> None:
          if not buffer:
              return
  
          exc_map = {
              TimeoutError: WriteTimeout,
              anyio.BrokenResourceError: WriteError,
          }
          with map_exceptions(exc_map):
              with anyio.fail_after(timeout):
                  await self._stream.send(item=buffer)
  
      async def aclose(self) -> None:
          await self._stream.aclose()
  
      async def start_tls(
          self,
          ssl_context: ssl.SSLContext,
          server_hostname: str = None,
          timeout: float = None,
      ) -> AsyncNetworkStream:
          exc_map = {
              TimeoutError: ConnectTimeout,
              anyio.BrokenResourceError: ConnectError,
          }
          with map_exceptions(exc_map):
              with anyio.fail_after(timeout):
                  ssl_stream = await anyio.streams.tls.TLSStream.wrap(
                      self._stream,
                      ssl_context=ssl_context,
                      hostname=server_hostname,
                      standard_compatible=False,
                      server_side=False,
                  )
          return AsyncIOStream(ssl_stream)
  
      def get_extra_info(self, info: str) -> typing.Any:
          if info == "ssl_object":
              return self._stream.extra(anyio.streams.tls.TLSAttribute.ssl_object, None)
          if info == "client_addr":
              return self._stream.extra(anyio.abc.SocketAttribute.local_address, None)
          if info == "server_addr":
              return self._stream.extra(anyio.abc.SocketAttribute.remote_address, None)
          if info == "socket":
              return self._stream.extra(anyio.abc.SocketAttribute.raw_socket, None)
          if info == "is_readable":
              sock = self._stream.extra(anyio.abc.SocketAttribute.raw_socket, None)
              return is_socket_readable(sock)
          return None
  
  
  class AsyncIOBackend(AsyncNetworkBackend):
      async def connect_tcp(
          self, host: str, port: int, timeout: float = None, local_address: str = None
      ) -> AsyncNetworkStream:
          exc_map = {
              TimeoutError: ConnectTimeout,
              OSError: ConnectError,
              anyio.BrokenResourceError: ConnectError,
          }
          with map_exceptions(exc_map):
              with anyio.fail_after(timeout):
                  stream: anyio.abc.ByteStream = await anyio.connect_tcp(
                      remote_host=host,
                      remote_port=port,
                      local_host=local_address,
                  )
          return AsyncIOStream(stream)
  
      async def connect_unix_socket(
          self, path: str, timeout: float = None
      ) -> AsyncNetworkStream:  # pragma: nocover
          exc_map = {
              TimeoutError: ConnectTimeout,
              OSError: ConnectError,
              anyio.BrokenResourceError: ConnectError,
          }
          with map_exceptions(exc_map):
              with anyio.fail_after(timeout):
                  stream: anyio.abc.ByteStream = await anyio.connect_unix(path)
          return AsyncIOStream(stream)
  
      async def sleep(self, seconds: float) -> None:
          await anyio.sleep(seconds)  # pragma: nocover
  