code: def send_file(filename, options = {})
           response['X-Sendfile'.freeze] = filename
           options[:filename] ||= File.basename(filename)
           filename = File.open(filename, 'rb'.freeze) # unless Iodine::Rack.public
           send_data filename, options
        end
docs: Same as {#send_data}, but accepts a file name (to be opened and sent) rather then a String.
  
   See {#send_data} for available options.