code: public static long computeHash64(CharSequence cs) {
          long h = HSTART;
          final long hmult = HMULT;
          final long[] ht = byteTable;
          final int len = cs.length();
          for (int i = 0; i < len; i++) {
              char ch = cs.charAt(i);
              h = (h * hmult) ^ ht[ch & 0xff];
              h = (h * hmult) ^ ht[(ch >>> 8) & 0xff];
          }
          return h;
      }
docs: Computes a 64bit hash code of a {@link CharSequence character sequence}.
  <p>
  Using a 64bit hash code minimizes collisions at the cost of size.
  </p>
  
  @param cs the {@link CharSequence character sequence} to hash
  @return the 64bit hash