size_t[10] data;
// creates a packed unsigned integer slice with max allowed value equal to `2^^6 - 1 == 63`.
auto packs = data[].bitpack!6;
assert(packs.length == data.length * size_t.sizeof * 8 / 6);
packs[$ - 1] = 24;
assert(packs[$ - 1] == 24);

packs.popFront;
assert(packs[$ - 1] == 24);