clone method
Implementation
BLAKE2b clone() {
final b2 = BLAKE2b();
b2._state.setAll(0, _state);
b2._buffer.setAll(0, _buffer);
b2._bufferLength = _bufferLength;
b2._ctr.setAll(0, _ctr);
b2._flag.setAll(0, _flag);
b2._lastNode = _lastNode;
b2._finished = _finished;
b2._vtmp.setAll(0, _vtmp);
b2._mtmp.setAll(0, _mtmp);
b2._paddedKey = _paddedKey?.clone();
b2._initialState = _initialState.clone();
return b2;
}