code: def process_jpeg_bytes(bytes_in, quality=DEFAULT_JPEG_QUALITY):
      
      bytes_out_p = ffi.new("char**")
      bytes_out_p_gc = ffi.gc(bytes_out_p, lib.guetzli_free_bytes)
  
      length = lib.guetzli_process_jpeg_bytes(
              bytes_in,
              len(bytes_in),
              bytes_out_p_gc,
              quality
              )
  
      if length == 0:
          raise ValueError("Invalid JPEG: Guetzli was not able to decode the image")  # noqa
  
      bytes_out = ffi.cast("char*", bytes_out_p_gc[0])
      return ffi.unpack(bytes_out, length)
docs: Generates an optimized JPEG from JPEG-encoded bytes.
  
      :param bytes_in: the input image's bytes
      :param quality: the output JPEG quality (default 95)
  
      :returns: Optimized JPEG bytes
      :rtype: bytes
  
      :raises ValueError: Guetzli was not able to decode the image (the image is
                          probably corrupted or is not a JPEG)
  
      .. code:: python
  
          import pyguetzli
  
          input_jpeg_bytes = open("./test/image.jpg", "rb").read()
          optimized_jpeg = pyguetzli.process_jpeg_bytes(input_jpeg_bytes)