cheat sheets.

== Rackup

hello.ru:
  require 'hello'

  use Rack::Reloader
  use Rack::CommonLogger
  use Rack::ShowExceptions
  use Rack::ShowStatus

  run HelloApp.new

run server:
  % rackup hello.ru


== Calling convention

  def call(env)
    [StatusCode, { "Header" => "Value" }, ["Body"]]
  end