class Tilt::Mapping

def extensions_for(template_class)
  res = []
  template_map.each do |ext, klass|
    res << ext if template_class == klass
  end
  lazy_map.each do |ext, choices|
    res << ext if choices.any? { |klass, file| template_class.to_s == klass }
  end
  res
end