 
     func testOpt() {
         let parser: Parser<String?, StringReader> =
-            (char(Character("a")) ^^ String.init).opt()
+            (char("a") ^^ String.init).opt()
 
         expectSuccess(parser: parser,
                       input: "a",


    func testMap() {
        let parser: Parser<String, StringReader> =
            char(Character("a"))
                ^^ { String($0).uppercased() }

        expectSuccess(parser: parser,
                      input: "a",


    func testRepMinMax() {
        let parser: Parser<[String], StringReader> =
            (char("a") ^^ String.init).rep(min: 2, max: 4)

        expectFailure(parser: parser,
                      input: "")
