bitpack

```rust let mut buff = [0; 4];

// write { let mut bitpack = BitPack::<&mut [u8]>::new(&mut buff); bitpack.write(10, 4).unwrap(); bitpack.write(1021, 10).unwrap(); bitpack.write(3, 2).unwrap(); bitpack.flush(); }

assert_eq!(buff, [0, 0, 247, 175]);

// read { let mut bitpack = BitPack::<&[u8]>::new(&buff); asserteq!(bitpack.read(4).unwrap(), 10); asserteq!(bitpack.read(10).unwrap(), 1021); assert_eq!(bitpack.read(2).unwrap(), 3); } ```