You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: farbfeld.rs
    path of file: ./repos/image/src/codecs
    
    the code of the file until where you have to start completion: //! Decoding of farbfeld images
//!
//! farbfeld is a lossless image format which is easy to parse, pipe and compress.
//!
//! It has the following format:
//!
//! | Bytes  | Description       
    
    fn read_rect(x: u32, y: u32, width: u32, height: u32, exp_wide: &[u16]) {
        let mut out_buf = [0u8; 64];
        FarbfeldDecoder::new(Cursor::new(RECTANGLE_IN))
            .unwrap()
            .read_rect(x, y, width, height, &mut out_buf, width as usize * 8)
            .unwrap();
        let exp = degenerate_pixels(exp_wide);
        assert_eq!(&out_buf[..exp.len()], &exp[..]);
    }