/*
  * Clear the report variable by overriding it with a new empty report
  */
 private void Clear() => _productStockReport = new ProductStockReport();
 /*
  * Take a collection of products in the parameter and create a new report
  */
 public ProductStockReportBuilder(IEnumerable <Product> products)
 {
     _products           = products;
     _productStockReport = new ProductStockReport();
 }