anchor.diff:  class Router
     attr_accessor :routes
   
  -  def initialize
  +  def initialize(&block)
       @routes = []
  -
  -    if block_given?
  -      block = Proc.new
  -      instance_eval(block)
  -    end
  +    instance_eval(&block) if block_given?
     end
   
     [:delete, :get, :head, :options, :patch, :post, :put, :trace].each do |verb|
  
positive.code: class Router
    attr_accessor :routes
  
    def initialize
      @routes = []
  
      if block_given?
        block = Proc.new
        instance_eval(block)
      end
    end
  
    [:delete, :get, :head, :options, :patch, :post, :put, :trace].each do |verb|
      self.define_method verb do |path, &block|
        routes << Route.new {matcher: path, handler: Proc.new &block }
      end
    end
  
  
negative.code: To use it we simply treat it like we would any Rack app:
  
  ```ruby
  router = Router.new do
    get '/cats' do
      [200, {}, ["Cats!"]]
    end
  end
  
  run router
  ```
  
  <%= gh_branch 'a-simple-rack-router', 'step-1' %>
  