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: 20170126154611_use_zone_timestamp_before_calculate_slip_expiration.rb
    path of file: ./repos/catarse/db/migrate
    
    the code of the file until where you have to start completion: class UseZoneTimestampBeforeCalculateSlipExpiration < ActiveRecord::Migration
  def up
    execute %Q{
CREATE OR REPLACE FUNCTION public.slip_expires_at(payment
    
  def down
    execute %Q{
CREATE OR REPLACE FUNCTION public.slip_expires_at(payments)
 RETURNS timestamp without time zone
 LANGUAGE sql
 STABLE
AS $function$
SELECT weekdays_from(public.slip_expiration_weekdays(), $1.created_at);
    $function$
;
}
  end