constructor(hashOrFactory, hashKey) {
	    this.hashKey = hashKey;

	    if (typeof hashOrFactory === "function") {
	      this.hashFactory = hashOrFactory;
	      this.hash = undefined;
	    } else {
	      this.hashFactory = undefined;
	      this.hash = hashOrFactory;
	    }

	    this.buffer = "";
	  }
@param {Hash | function(): Hash} hashOrFactory function to create a hash
@param {string=} hashKey key for caching