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: 20181219171638_add_impressions_template_theme.rb
    path of file: ./repos/code_fund_ads/db/migrate
    
    the code of the file until where you have to start completion: class AddImpressionsTemplateTheme < ActiveRecord::Migration[5.2]
  def up
    remove_column :impressions, :campaign_name
    remove_column :impressions
    
  def down
    remove_column :impressions, :ad_template
    remove_column :impressions, :ad_theme
    add_column :impressions, :campaign_name, :string
    add_column :impressions, :property_name, :string
    add_index :impressions, :campaign_name
    add_index :impressions, :property_name
  end