writeCopy(start, end) {
    assertNatNumber(start);
    assertNatNumber(end);
    const state = this.#state;
    const size = end - start;
    this.ensureCanWrite(size);
    state.bytes.copyWithin(state.index, start, end);
    state.index += size;
    state.length = Math.max(state.index, state.length);
  }
@param {number} start
@param {number} end