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: 20190218152423_create_simple_admin_core_migration.rb
    path of file: ./repos/simpleadmin/db/migrate
    
    the code of the file until where you have to start completion: class CreateSimpleAdminCoreMigration < ActiveRecord::Migration[5.2]
  def change
    create_table :simple_admin_entities do |t|
      t.string :model_klass_name, null: false
      t.string :label

      t.references :project

      t.string :icon
      t.string :slug

      t.boolean :status, default: true

      t.timestamps null: false
    end

    create_table :simple_admin_entity_fields do |t|
      t.string :name
      t.string :label
      t.string :slug

      t.integer :entity_field_type_id, null: false
      t.integer :entity_id, null: false

      t.integer :presentation
      t.integer :sort_order, default: 1

      t.boolean :sorting, default: false
      t.boolean :search_indexable, default: false

      t.timestamps null: false
    end

    create_table :simple_ad
    
  def change
    create_table :simple_admin_entities do |t|
      t.string :model_klass_name, null: false
      t.string :label

      t.references :project

      t.string :icon
      t.string :slug

      t.boolean :status, default: true

      t.timestamps null: false
    end

    create_table :simple_admin_entity_fields do |t|
      t.string :name
      t.string :label
      t.string :slug

      t.integer :entity_field_type_id, null: false
      t.integer :entity_id, null: false

      t.integer :presentation
      t.integer :sort_order, default: 1

      t.boolean :sorting, default: false
      t.boolean :search_indexable, default: false

      t.timestamps null: false
    end

    create_table :simple_admin_entity_field_types do |t|
      t.string :name,     null: false
      t.string :template, null: false

      t.timestamps null: false
    end

    create_table :simple_admin_widgets do |t|
      t.string :name
      t.string :icon
      t.string :slug

      t.integer :width

      t.references :project
      t.references :widget_category
      t.references :entity

      t.boolean :status, default: true

      t.integer :sort_order, default: 1

      t.timestamps null: false
    end

    create_table :simple_admin_widget_categories do |t|
      t.string :name
      t.string :label
      t.string :template

      t.timestamps null: false
    end
  end