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: 20170707122626_create_visits.rb
    path of file: ./repos/docker-rails/db/migrate
    
    the code of the file until where you have to start completion: class CreateVisits < ActiveRecord::Migration[5.1]
  def change
    create_table :visits do |t|
      t.string :visit_token
      t.string :visitor_token

      # the rest are recommended but optional
      # simply remove the columns you don't want

      # standard
      t.string :ip
      t.text :user_agent
      t.text :referrer
      t.text :landing_page

      # user
      t.integer :user_id
      # add t.string :user_type if polymorphic

      # traffic source
      t.string :referring_domain
      t.string :search_keyword

      # technology
      t.string :browser
      t.string :os
      t.string :device_type
      t.integer :screen_height
      t.integer :screen_width

      # locati
    
  def change
    create_table :visits do |t|
      t.string :visit_token
      t.string :visitor_token

      # the rest are recommended but optional
      # simply remove the columns you don't want

      # standard
      t.string :ip
      t.text :user_agent
      t.text :referrer
      t.text :landing_page

      # user
      t.integer :user_id
      # add t.string :user_type if polymorphic

      # traffic source
      t.string :referring_domain
      t.string :search_keyword

      # technology
      t.string :browser
      t.string :os
      t.string :device_type
      t.integer :screen_height
      t.integer :screen_width

      # location
      t.string :country
      t.string :region
      t.string :city
      t.string :postal_code
      t.decimal :latitude
      t.decimal :longitude

      # utm parameters
      t.string :utm_source
      t.string :utm_medium
      t.string :utm_term
      t.string :utm_content
      t.string :utm_campaign

      # native apps
      # t.string :platform
      # t.string :app_version
      # t.string :os_version

      t.timestamp :started_at
    end

    add_index :visits, [:visit_token], unique: true
    add_index :visits, [:user_id]
  end
end