     a `{{% CONTENT_TYPE:TEXT }}` pragma tag.
     
         // The strong RenderFunction below wraps a section in a <strong> HTML tag.
-        let strong: RenderFunction = { (info: RenderingInfo, _) -> Rendering? in
-            let rendering = info.tag.render(info.context)
-            return Rendering("<strong>\(rendering!.string)</strong>", .HTML)
+        let strong: RenderFunction = { (info: RenderingInfo) -> Rendering in
+            let rendering = try info.tag.render(info.context)
+            return Rendering("<strong>\(rendering.string)</strong>", .HTML)
         }
 
-        let template = Template(string: "{{#strong}}Hello {{name}}{{/strong}}")!
+        let template = try! Template(string: "{{#strong}}Hello {{name}}{{/strong}}")
         template.registerInBaseContext("strong", Box(strong))
 
         // Renders "<strong>Hello Arthur</strong>"
-        template.render(Box(["name": Box("Arthur")]))!
+        try! template.render(Box(["name": Box("Arthur")]))
     
     - parameter context: The context stack for evaluating mustache tags
     - parameter error:   If there is a problem rendering the tag, upon return

            }
        }

        let template = Template(string: "{{object}}, {{#object}}...{{/object}}")!

        // Renders "variable, section"
        template.render(Box(["object": Box(render)]))!
    */
    public let type: TagType
    

    /**
    The type of the tag: variable or section:
    
        let render: RenderFunction = { (info: RenderingInfo) in
            switch info.tag.type {
            case .Variable:
                return Rendering("variable")
