This module defines an analogue to Box<[bool]>, as Box<BitSlice> cannot be constructed or used in any way. Like Box<[T]>, this is a heap allocation that can modify its contents, but cannot resize the collection. The BitBox value is an owning *BitSlice pointer, and can be used to access its contents without any decoding.
You should generally prefer BitVec or BitArray; however, very large BitArrays are likely better served being copied into a BitBox rather than being boxed themselves when moved into the heap.