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: expenses_by_product_nature_category_cells_controller.rb
    path of file: ./repos/ekylibre/app/controllers/backend/cells
    
    the code of the file until where you have to start completion: module Backend
  module Cells
    class ExpensesByProductNatureCategoryCells
    
      def show
        f = current_user.current_financial_year
        if f
          @financial_year = f
          @started_at = f.started_on.to_time
          @stopped_at = f.stopped_on.to_time
        end