See server0.rb - server3.rb. Each file is self-documenting.

Starting with server3.rb, modify the app to add the following features:

• Visiting "GET /signup" responds with an HTML page with a form to add your email to a list.
• Visiting "POST /signup" adds the email address to the list (storing it as a global array is fine for now)
• Visiting "GET /attendees" returns a page listing all the signups

• Save attendees to a database or file.
• Write simple templating method(s) to add 'layout' functionality.

• Built a simple framework that lets you write code like sinatra.