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: 20230607083454_time_accounting_enhancements.rb
    path of file: ./repos/zammad/db/migrate
    
    the code of the file until where you have to start completion: # Copyright (C) 2012-2024 Zammad Foundation, https://zammad-foundation.org/

class TimeAccountingEnhancements < ActiveRecord::Migration[5.0]
  def change
    # return if it's a new setup
    return if !Setting.exists?(name: 'system_init_done')

    create_ticket_time_accounting_types_table
    create_ticket_time_accounting_unit_settings
    create_ticket_time_accounting_type_settings
  end

  private

  def create_ticket_time_accounting_types_ta
    
  def create_ticket_time_accounting_type_settings
    Setting.create_if_not_exists(
      title:       'Time Accounting Types',
      name:        'time_accounting_types',
      area:        'Web::Base',
      description: 'Defines if the time accounting types are enabled.',
      options:     {
        form: [
          {},
        ],
      },
      preferences: {
        authentication: true,
        permission:     ['admin.time_accounting'],
      },
      state:       false,
      frontend:    true
    )

    Setting.create_if_not_exists(
      title:       'Time Accounting Default Type',
      name:        'time_accounting_type_default',
      area:        'Web::Base',
      description: 'Defines the default time accounting type.',
      options:     {
        form: [
          {},
        ],
      },
      preferences: {
        authentication: true,
        permission:     ['admin.time_accounting'],
      },
      state:       '',
      frontend:    true
    )
  end