 filter from the Standard Library:
 
     // Register StandardLibrary.each for the key "each":
-    let template = Template(string: "<{{# each(dictionary) }}{{@key}}:{{.}}, {{/}}>")!
+    let template = try! Template(string: "<{{# each(dictionary) }}{{@key}}:{{.}}, {{/}}>")
     template.registerInBaseContext("each", Box(StandardLibrary.each))
 
     // Renders "<firstName:Freddy, lastName:Mercury,>"
     let dictionary: [String: String?] = ["firstName": "Freddy", "lastName": "Mercury"]
-    let rendering = template.render(Box(["dictionary": dictionary]))!
+    let rendering = try! template.render(Box(["dictionary": dictionary]))
 
 
 ### Unwrapping from MustacheBox

    })

    // Renders "key:a"
    let template = Template(string:"{{a}}")!
    template.render(box)!


### filter



- parameter dictionary: A dictionary of optional values that conform to the
                        `MustacheBoxable` protocol.

- returns: A MustacheBox that wraps `dictionary`
*/
