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: 20180916002448_add_trigram_index_to_artist_urls.rb
    path of file: ./repos/danbooru/db/migrate
    
    the code of the file until where you have to start completion: class AddTrigramIndexToArtistURLs < ActiveRecord::Migration[5.2]
  def change
    execute "set statement_timeout = 0"

    change_table :artist_urls do |t|
      t.remove_index column: :url, name: :index_artist_urls_on_url
      t.remove_index column: :url, name: :index_artist_urls_on_url_pattern, opclass: :text_pattern_ops
      t.remove_index col
    
  def change
    execute "set statement_timeout = 0"

    change_table :artist_urls do |t|
      t.remove_index column: :url, name: :index_artist_urls_on_url
      t.remove_index column: :url, name: :index_artist_urls_on_url_pattern, opclass: :text_pattern_ops
      t.remove_index column: :normalized_url, name: :index_artist_urls_on_normalized_url

      t.index :url, name: :index_artist_urls_on_url_trgm, using: :gin, opclass: :gin_trgm_ops
      t.index :normalized_url, name: :index_artist_urls_on_normalized_url_trgm, using: :gin, opclass: :gin_trgm_ops
    end
  end