code: boolean get(int bitIndex) {
          int wordIndex = wordIndex(bitIndex);
          long bitMask = 1L << bitIndex;
          return (words[wordIndex] & bitMask) != 0;
      }
docs: Gets the bit at the specified index.
  
  @param bitIndex a bit index
  @return state of bitIndex that can be {@code true} or {@code false}
  @throws IndexOutOfBoundsException if the specified index is negative