gistfile1.rb

post '/press' do
  digits = params[:digits]
  
  if digits != "1"
    redirect '/'
  end
  
  content_type 'text/xml', :charset => 'utf-8'
  builder do |xml|
    xml.instruct!
    xml.Response do  
      xml.Say("You pressed #{digits}")
    end
  end
end