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: 20130425024459_create_keep_disks.rb
    path of file: ./repos/arvados/services/api/db/migrate
    
    the code of the file until where you have to start completion: # Copyright (C) The Arvados Authors. All rights reserved.
#
# SPDX-License-Identifier: AGPL-3.0

class CreateKeepDisks < ActiveRecord::Migration[4.2]
  def change
    create_table :keep_disks do |t|
      t.string :uuid, :null => false
      t.string :owner, :null => false
      t.string :modified_by_client
      t.string :modified_by_user
      t.datetime :modified_at
      t.string :ping_secret, :null => false
      t.string :node_uuid
      t.string :filesystem_uuid
      t.integer :bytes_total
      t.integer :bytes_free
      t.boolean :is_readable, :null => false, :default => true
      t.boolean :is_writabl
    
  def change
    create_table :keep_disks do |t|
      t.string :uuid, :null => false
      t.string :owner, :null => false
      t.string :modified_by_client
      t.string :modified_by_user
      t.datetime :modified_at
      t.string :ping_secret, :null => false
      t.string :node_uuid
      t.string :filesystem_uuid
      t.integer :bytes_total
      t.integer :bytes_free
      t.boolean :is_readable, :null => false, :default => true
      t.boolean :is_writable, :null => false, :default => true
      t.datetime :last_read_at
      t.datetime :last_write_at
      t.datetime :last_ping_at

      t.timestamps
    end
    add_index :keep_disks, :uuid, :unique => true
    add_index :keep_disks, :filesystem_uuid
    add_index :keep_disks, :node_uuid
    add_index :keep_disks, :last_ping_at
  end