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: order_cancellations.rb
    path of file: ./repos/solidus/core/app/models/spree
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

# This class represents all of the actions one can take to modify an Order after it is complete
class Spree::OrderCancellations
  extend ActiveModel::Tr
    
  def short_ship_unit(inventory_unit, created_by: nil)
    unit_cancel = Spree::UnitCancel.create!(
      inventory_unit: inventory_unit,
      reason: Spree::UnitCancel::SHORT_SHIP,
      created_by: created_by
    )
    unit_cancel.adjust!
    inventory_unit.cancel!

    unit_cancel
  end