Idea for nested steps functionality

indes.js

class StepNode {
	const stepName;
	const func;
	const that;
	const args;
	const nestedStepNode;
	
	const getTail = function() {
		tmp = this;
		while (tmp.nestedStepNode != null) {
			tmp = tmp.nestedStepNode;
		}
		return tmp;
	}
}
	

let step = new StepNode();

Allure.prototype.createStep = function(name, stepFunc, nested) {
    let tmpStep = new StepNode();
	tmpStep.stepname = this._format(name, Array.prototype.slice.call(arguments, 0)),
        status = 'passed',
        result;
	tmpStep.func = stepFunc;
	tmpStep.that = this;
	tmpStep.args = arguments;
	tmpStep.nestedStepNode = null;
		
	if (nested) {
		step.getTail().nestedStepNode = nested; // find last node with nested === null and assign just created to it
	} else {
		this.performStepCreation(step);
		step = tmpStep;
	}
};

Allure.prototype.performStepCreation = function (stepNode) {
	if (stepNode.nestedStepNode) {
		performStepCreation(stepNode.nestedStepNode) && performStepCreation(stepNode);
	} else {
		var stepName = that._format(name, Array.prototype.slice.call(arguments, 0)),
            status = 'passed',
            result;
        that._allure.startStep(stepName);
        try {
            result = stepFunc.apply(this, arguments);
        }
        catch(error) {
            status = 'broken';
            throw error;
        }
        finally {
            if(that.isPromise(result)) {
                result.then(function() {
                    that._allure.endStep('passed');
                }, function() {
                    that._allure.endStep('broken');
                });
            } else {
                that._allure.endStep(status);
            }
        }
        return result;
	}
}