class Capybara::Selenium::FirefoxNode

def upload(local_file)
  return nil unless local_file
  raise ArgumentError, "You may only upload files: #{local_file.inspect}" unless File.file?(local_file)
  file = ::Selenium::WebDriver::Zipper.zip_file(local_file)
  bridge.http.call(:post, "session/#{bridge.session_id}/file", file: file)['value']
end