```ruby
module RubyWedding
  class Invitation < ActiveRecord::Base
    has_many :guests, class_name: "RubyWedding::Guest"

    accepts_nested_attributes_for :guests

    validates :notes, length: { maximum: 2000 }

    def self.find_by_guest_surname(surname)
      includes(:guests).where('ruby_wedding_guests.surname' => surname).distinct
    end

    def guest_list
      guests.map(&:fullname).to_sentence(last_word_connector: ' & ')
    end

    def contains_children?
      guests.any?(&:child?)
    end

  end
end
```

Add .all to guests in guest_list
user
```ruby
module RubyWedding
  class Invitation < ActiveRecord::Base
    has_many :guests, class_name: "RubyWedding::Guest"

    accepts_nested_attributes_for :guests

    validates :notes, length: { maximum: 2000 }

    def self.find_by_guest_surname(surname)
      includes(:guests).where('ruby_wedding_guests.surname' => surname).distinct
    end

    def guest_list
      guests.all.map(&:fullname).to_sentence(last_word_connector: ' & ')
    end

    def contains_children?
      guests.any?(&:child?)
    end

  end
end
```
assistant