```ruby
module Discard::Model
  extend ActiveSupport::Concern

  included do
    scope :kept, ->{ where(discarded_at: nil) }
    scope :discarded, ->{ where.not(discarded_at: nil) }
    scope :with_discarded, ->{ unscope(where: :discarded_at) }
  end

  def discarded?
    !!discarded_at
  end

  def discard
    touch(:discarded_at) unless discarded?
  end
end
```

Use nested, not rails-style, module declaration
user
```ruby
module Discard
  module Model
    extend ActiveSupport::Concern

    included do
      scope :kept, ->{ where(discarded_at: nil) }
      scope :discarded, ->{ where.not(discarded_at: nil) }
      scope :with_discarded, ->{ unscope(where: :discarded_at) }
    end

    def discarded?
      !!discarded_at
    end

    def discard
      touch(:discarded_at) unless discarded?
    end
  end
end
```
assistant