code: function valueShouldBeInsertedAsHTML(value) {
  	return value !== null && typeof value === "object" && (
  		typeof value[toDOMSymbol] === "function" ||
  		typeof value[viewInsertSymbol] === "function" ||
  		typeof value.nodeType === "number" );
  }
docs: DOM, safeString or the insertSymbol can opt-out of updating as text