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: notifier.rb
    path of file: ./repos/enju_leaf/app/mailers
    
    the code of the file until where you have to start completion: class Notifier < ApplicationMailer
  def message_notification(message_id)
    message = Message.find(message_id)
    from = "#{LibraryGroup.system_name(message.receiver.profile.locale)} <#{LibraryGroup.site_config.email}>"
    if message.subject
      subject = message.subject
    else
      subject = I18n.t('message.new_message_from_library', library
    
  def manifestation_info(user_id, manifestation_id)
    user = User.find(user_id)
    manifestation = Manifestation.find(manifestation_id)
    from = "#{LibraryGroup.system_name(user.profile.locale)} <#{LibraryGroup.site_config.email}>"
    subject = "#{manifestation.original_title} : #{LibraryGroup.system_name(user.profile.locale)}"
    @user = user
    @items = Pundit.policy_scope!(user, manifestation.items)
    @manifestation = manifestation
    mail(from: from, to: user.email, subject: subject)
  end