You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 20180714153306_remove_comments_without_user.rb
    path of file: ./repos/rgsoc-teams/db/migrate
    
    the code of the file until where you have to start completion: class Rem
    
  def up
    execute <<~SQL
      DELETE
      FROM comments
      WHERE user_id NOT IN (SELECT id FROM users)
    SQL
  end