module ActionView::Template::Handlers

and should return the rendered template as a String.
The handler must respond to `:call`, which will be passed the template
extensions. This can be used to implement new template types.
Register an object that knows how to handle template files with the given

def register_template_handler(*extensions, handler)
  raise(ArgumentError, "Extension is required") if extensions.empty?
  extensions.each do |extension|
    @@template_handlers[extension.to_sym] = handler
  end
  @@template_extensions = nil
end