Sanitize preserving tags inside a code block

sanitize_preserving_code.rb

require 'nokogiri'

def sanitize_preserving_code(content)
  doc = Nokogiri::HTML::DocumentFragment.parse content
  doc.css('code').each do |code|
    code.inner_html = h code.inner_html
  end
  sanitize doc.to_html, :tags => %w(strong em code br a) 
end