142 struct BitString {  struct
235   BitString() = default;  argument
238   bool operator==(const BitString& other) const {
243   bool operator!=(const BitString& other) const {
249     return (*this) == BitString{};  in IsEmpty()  argument
255   BitString Truncate(size_t end) {  in Truncate()  argument
257     BitString copy = *this;  in Truncate()
270   friend std::ostream& operator<<(std::ostream& os, const BitString& bit_string);
277 static_assert(BitSizeOf<BitString::StorageType>() >=  argument
278                   BitString::GetBitLengthTotalAtPosition(BitString::kCapacity),
282 inline std::ostream& operator<<(std::ostream& os, const BitString& bit_string) {
291     os << static_cast<BitString::StorageType>(bc);