code: async def file_stream(
      location,
      status=200,
      chunk_size=4096,
      mime_type=None,
      headers=None,
      filename=None,
      _range=None,
  ):
      
      headers = headers or {}
      if filename:
          headers.setdefault(
              "Content-Disposition", 'attachment; filename="{}"'.format(filename)
          )
      filename = filename or path.split(location)[-1]
  
      _file = await open_async(location, mode="rb")
  
      async def _streaming_fn(response):
          nonlocal _file, chunk_size
          try:
              if _range:
                  chunk_size = min((_range.size, chunk_size))
                  await _file.seek(_range.start)
                  to_send = _range.size
                  while to_send > 0:
                      content = await _file.read(chunk_size)
                      if len(content) < 1:
                          break
                      to_send -= len(content)
                      await response.write(content)
              else:
                  while True:
                      content = await _file.read(chunk_size)
                      if len(content) < 1:
                          break
                      await response.write(content)
          finally:
              await _file.close()
          return  # Returning from this fn closes the stream
  
      mime_type = mime_type or guess_type(filename)[0] or "text/plain"
      if _range:
          headers["Content-Range"] = "bytes %s-%s/%s" % (
              _range.start,
              _range.end,
              _range.total,
          )
          status = 206
      return StreamingHTTPResponse(
          streaming_fn=_streaming_fn,
          status=status,
          headers=headers,
          content_type=mime_type,
      )
docs: Return a streaming response object with file data.
  
      :param location: Location of file on system.
      :param chunk_size: The size of each chunk in the stream (in bytes)
      :param mime_type: Specific mime_type.
      :param headers: Custom Headers.
      :param filename: Override filename.
      :param _range: