Laravel\Cashier\Billable::onTrial PHP Method

    public function onTrial($subscription = 'default', $plan = null)
    {
        if (func_num_args() === 0 && $this->onGenericTrial()) {
            return true;
        }
        $subscription = $this->subscription($subscription);
        if (is_null($plan)) {
            return $subscription && $subscription->onTrial();
        }
        return $subscription && $subscription->onTrial() && $subscription->braintree_plan === $plan;
    }