```ruby
module TrafficLightController
  class Config
    def initialize
      @config = Hashie::Mash.new(YAML.load_file('./config/config.yml'))
    end

    def method_missing(meth, *args, &block)
      return config[meth.to_s] if config.has_key?(meth.to_s)
      super
    end

    def respond_to?(meth)
      config.has_key?(meth.to_s) || super
    end

    private

    attr_reader :config
  end
end
```

Use a better argument name
user
```ruby
module TrafficLightController
  class Config
    def initialize
      @config = Hashie::Mash.new(YAML.load_file('./config/config.yml'))
    end

    def method_missing(method_name, *args, &block)
      return config[method_name.to_s] if config.has_key?(method_name.to_s)
      super
    end

    def respond_to?(method_name)
      config.has_key?(method_name.to_s) || super
    end

    private

    attr_reader :config
  end
end
```
assistant