docs: public void writeTo(OutputStream out) throws IOException {
      /*
       * Serial form:
       * 1 signed byte for the strategy
       * 1 unsigned byte for the number of hash functions
       * 1 big endian int, the number of longs in our bitset
       * N big endian longs of our bitset
       */
      DataOutputStream dout = new DataOutputStream(out);
      dout.writeByte(SignedBytes.checkedCast(strategy.ordinal()));
      dout.writeByte(UnsignedBytes.checkedCast(numHashFunctions)); // note: checked at the c'tor
      dout.writeInt(bits.data.length);
      for (long value : bits.data) {
        dout.writeLong(value);
      }
    }