kwargs.rb

class Foo
  def initialize(target)
    @target = target
  end

  if RUBY_VERSION > "2.7"
    def method_missing(method, *args, **kwargs, &block)
      @target.send(method, *args, **kwargs, &block)
    end
  else
    def method_missing(method, *args, &block)
      @target.send(method, *args, &block)
    end
    ruby2_keywords(:method_missing) if respond_to?(:ruby2_keywords, true)
  end
end