docs: async def file(location, mime_type=None, headers=None, _range=None):
      '''Return a response object with file data.
  
      :param location: Location of file on system.
      :param mime_type: Specific mime_type.
      :param headers: Custom Headers.
      :param _range:
      '''
      filename = path.split(location)[-1]
  
      async with open_async(location, mode='rb') as _file:
          if _range:
              await _file.seek(_range.start)
              out_stream = await _file.read(_range.size)
              headers['Content-Range'] = 'bytes %s-%s/%s' % (
                  _range.start, _range.end, _range.total)
          else:
              out_stream = await _file.read()
  
      mime_type = mime_type or guess_type(filename)[0] or 'text/plain'
  
      return HTTPResponse(status=200,
                          headers=headers,
                          content_type=mime_type,
                          body_bytes=out_stream)