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: 20170702234704_add_tba_to_media.rb
    path of file: ./repos/kitsu-server/db/migrate
    
    the code of the file until where you have to start completion: class AddTbaToMedia < ActiveRecord::Migration[4.2]
  def change
    %i[anime dramas].each do |table|
      change_table table do |t|
        t.string :tba
   
    
  def change
    %i[anime dramas].each do |table|
      change_table table do |t|
        t.string :tba
        t.remove :started_airing_date_known
      end
    end

    add_column :manga, :tba, :string
  end