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: 20200508101630_convert_frontend_shipping_method_to_both.rb
    path of file: ./repos/openfoodnetwork/db/migrate
    
    the code of the file until where you have to start completion: # frozen_
    
  def up
    # The display_on value front_end is not working
    #   (it's not being used in the back office to ignore shipping methods marked as front_end)
    # So, here we are converting all entries to the more generic "both" option
    #   both is represented as nil in the database
    # # This enables us to remove the front_end option from the code
    execute("UPDATE spree_shipping_methods SET display_on = null WHERE display_on = 'front_end'")
  end