Testing sessionStorage using JS executor

JSSessionStorage.cs

//Set item value
   public void setItem(String itemName, String itemValue) {
   ((JavascriptExecutor) driver).executeScript("window.sessionstorage.setitem(itemName, itemValue)");
}

   //Get item value
   public String getItem(String itemValue) {
   return (String) ((JavascriptExecutor) driver).executeScript(String.format(
           "return window.sessionstorage.getItem('%s');", itemValue));
}