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: 20200618220501_add_owner_type_to_pay.rb
    path of file: ./repos/limestone/db/migrate
    
    the code of the file until where you have to start completion: # frozen_stri
    
  def change
    # add_column :pay_charges, :owner_type, :string
    add_column :pay_subscriptions, :owner_type, :string

    # Backfill owner_type column to match your Billable model
    Pay::Charge.update_all owner_type: "User"
    Pay::Subscription.update_all owner_type: "User"
  end