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: 20200821212880_create_mailboxer.mailboxer_engine.rb
    path of file: ./repos/hyrax/.dassie/db/migrate
    
    the code of the file until where you have to start completion: # This migration
    
  def self.down
  #Tables
    remove_foreign_key "mailboxer_receipts", :name => "receipts_on_notification_id"
    remove_foreign_key "mailboxer_notifications", :name => "notifications_on_conversation_id"

  #Indexes
    drop_table :mailboxer_receipts
    drop_table :mailboxer_conversations
    drop_table :mailboxer_notifications
  end