         case "\n".utf8Constant:
             return .Newline
             
-            // Comments.
+        // Comments.
         case "#".utf8Constant:
             // Scan to the end of the line.
             while let c = look() {

            }
            return .Whitespace

            // Strings.
        case "\"".utf8Constant:
            // Scan to the end of the string.
            //

            }
            return .StringLiteral(value: String(utf8[Range(start: startIndex.advancedBy(1), end: endIndex)]))

        // Numeric literals.
        //
        // NOTE: It is important we parse this ahead of identifiers, as
        // numbers are valid identifiers but should be reconfigured as such.
        case let c where c.isNumberInitialChar():
            // Scan to the end of the number.
            while let c = look() where c.isNumberChar() {
