Simplest way to get 404 with Silverstripe 3.6.5

<%- if @topic_view.topic.tags.present? %>
<%= t 'js.tagging.tags' %>: <%- @topic_view.topic.tags.each do |t| %> <%= t %> <%- end %>
<% end %>

Silverstripe Version: 3.6.5

Question:
What’s the simplest way to get 404 response code with Silverstripe 3.6.5? Thank you

return $this->httpError(404);

More info: