CreateEvents.boilerHeatHandler((event) => {
  /**
   * Explanation of Heat Level:
   * -1: This block does not provide heat in any form.
   * 0 : This block provides passive heat. (Like unfueled blaze burners)
   * 1 : This block provides 1 unit of heat (1 green bar in the status, like fueled blaze burners)
   * 2 : This block provides 2 units of heat (like blaze-caked burners)
   * X : This block provides X units of heat, which is X green bars in the status
   *
   * Notice that the callback is invoked only when there's an update signal to the boilers.
   * Like a change of blockstate in adjacent blocks, breaking/placing, etc.
   */

  /**
   * Register a heater for a single block.
   * The parameter in the callback is a BlockContainerJS.
   */
  event.add("minecraft:diamond_block", (block) => {
    return 2;
  });

  /**
   * Register a heater for a block predicate.
   */
  event.addAdvanced("#minecraft:logs", (block) => {
    if (block.id === "minecraft:oak_log") {
      return 1;
    } else {
      return 2;
    }
  });
});