Derive Macro BitEncode 

#[derive(BitEncode)]
{
    // Attributes available to this derive:
    #[bit_stream]
    #[nested]
    #[br]
    #[bw]
    #[brw]
    #[reserved]
    #[reserved_with]
}

Derives a bnb::BitEncode impl — the dual of BitDecode, writing the struct’s named fields in order to a bnb::BitWriter bit cursor. Shares BitDecode’s right-tool guard and #[bit_stream(...)] override.