code: public boolean contains0(int idx) {
        if (idx < 0) throw new IndexOutOfBoundsException("idx < 0: " + idx);
        idx -= _bitoff;
        return (idx >= 0) && (idx < _nbits) &&
                (_val[_byteoff + (idx >> 3)] & ((byte)1 << (idx & 7))) != 0;
      }
docs: /* SET IN STONE FOR MOJO VERSION "1.00" - DO NOT CHANGE