     
     private class func performXMLExport(_ sheets: [ExcelSheet], fileName: String) -> URL? {
         struct RemainingSpan {
-            var remainingRows : Int
-            var colSpan : Int
-            var description : String {
+            var remainingRows: Int
+            var colSpan: Int
+            var description: String {
                 return "remainingRows: \(remainingRows), colSpan: \(colSpan)"
             }
         }
         let file = fileUrl(name: fileName)
         
         // all styles for this wokrbook
-        var styles = [String : String]() // id : value
+        var styles = [String: String]() // id : value
         
         // adds new style, returns it's ID
         let appendStyle: (String)->String = {

        var a: CGFloat = 0
        self.getRed(&r, green: &g, blue: &b, alpha: &a)
        
        if (includeAlpha) {
            return String(format: "#%02X%02X%02X%02X", Int(r * 255), Int(g * 255), Int(b * 255), Int(a * 255))
        } else {
            return String(format: "#%02X%02X%02X", Int(r * 255), Int(g * 255), Int(b * 255))

        rowspan = nil
    }
    
    public init(_ value: String, _ attributes: [TextAttribute], _ type: DataType = .string, 
                colspan: Int? = nil, rowspan: Int? = nil) {
        self.value = value
        self.attributes = attributes
        self.colspan = colspan
