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: notification.rb
    path of file: ./repos/zammad/app/models/transaction
    
    the code of the file until where you have to start completion: # Copyright (C) 2012-2024 Zammad Foundation, https
    
  def perform

    # return if we run import mode
    return if Setting.get('import_mode')
    return if @item[:object] != 'Ticket'
    return if @params[:disable_notification]

    ticket = Ticket.find_by(id: @item[:object_id])
    return if !ticket

    if @item[:article_id]
      article = Ticket::Article.find(@item[:article_id])

      # ignore notifications
      sender = Ticket::Article::Sender.lookup(id: article.sender_id)
      if sender&.name == 'System'
        return if @item[:changes].blank? && article.preferences[:notification] != true

        if article.preferences[:notification] != true
          article = nil
        end