             try parseLongOption(characters)
         }
         try checkActiveOption()
-        try parsers.forEach { (_, parser) in
+        for (_, parser) in parsers {
             try parser.validate()
         }
     }

    private func parseOptions(_ options: [OptionProtocol], withArgs args: ArraySlice<String>, operandValues: inout [String]) throws {
        
        var parsers = [String: Parser]()
        options.forEach { option in
            let parser = (option as! Parsable).parser
            if let longName = option.name.long {
                parsers[longName] = parser

        }
        
        // Parse options and operands
        for (name, value) in fields {
            if value is OptionProtocol {
                let option = value as! OptionProtocol
                try checkOptionName(option.name)
