```ruby
class AddParentToPage < ActiveRecord::Migration
  def change
    add_column :pages, :parent_id, :integer
    add_index :parent_id
  end
end
```

Fix syntax error in pages migration
user
```ruby
class AddParentToPage < ActiveRecord::Migration
  def change
    add_column :pages, :parent_id, :integer
    add_index :pages, :parent_id
  end
end
```
assistant