Fatal error: Can't use function return value in write context

If you are getting the following error with WooCommerce Amazon Fulfillment activated:
Fatal error: Can't use function return value in write context in /home/site/public_html/wp-content/plugins/ns-fba-for-woocommerce/lib/class-ns-fba-outbound.php on line 491  
The cause of this problem is that the hosting environment you are using has a PHP version older than 5.5. Please check with your host about upgrading to 5.5 or later or find the PHP version management tool in cPanel and set it to 5.5 or higher. PHP version 5.4 was released in March 2012 and is no longer supported by PHP as of Sept 2015. WooCommerce Amazon Fulfillment is only compatible on PHP 5.5 or higher.    

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