pub fn from_u8(b: u8) -> Result<ChunkType, u8> {
        match b {
            0xFF => Ok(ChunkType::Stream),
            0x00 => Ok(ChunkType::Compressed),
            0x01 => Ok(ChunkType::Uncompressed),
            0xFE => Ok(ChunkType::Padding),
            b => Err(b),
        }
    }
Converts a byte to one of the four defined chunk types represented by
a single byte. If the chunk type is reserved, then it is returned as
an Err.
src/frame.rs