docs: int set(int bitIndex, boolean value) {
          int wordIndex = wordIndex(bitIndex);
          long bitMask = 1L << bitIndex;
          int previous = (words[wordIndex] & bitMask) != 0 ? 1 : 0;
          if (value) {
              words[wordIndex] |= bitMask;
          } else {
              words[wordIndex] &= ~bitMask;
          }
          return previous;
      }