Creating updating tags on button click event

VisitorTagsExample.cs

private void CheckinButton_OnClick(object sender, EventArgs e)
{
    var button = sender as Button;
    if (button == null)
        return;
        
    string location = button.CommandArgument;

    // Retrieve the visitor from Sitecore Analytics
    var visitor = Sitecore.Analytics.Tracker.Visitor;
    if (visitor == null)
        return;

    // Get the Tag named LocationsCheckedIn
    var visitorTags = visitor.Tags.Find("LocationsCheckedIn");
    if (visitorTags == null)
    {
        // If the tag is not present we add one with the name LocationsCheckedIn
        // and pass in the TagValue, in this case the location
        visitor.Tags.Add("LocationsCheckedIn", location + "|");
    }
    else
    {
        // If the tag does exist we retrieve and append to the value creating a
        // pipe separated list of locations the user has checked in
        StringBuilder tagValue = new StringBuilder(visitorTags.TagValue);
        if (!visitorTags.TagValue.EndsWith("|"))
            tagValue.Append("|");
        tagValue.Append(location + "|");
    }
    
     //Any subsequent code to complete Checkin event
}