```ruby
#!/usr/bin/env ruby
# vim: et ts=2 sw=2

require "sinatra"
require "octokit"
require "redis"


# Init

redis = Redis.new
NS = "pullstate"
TTL = 60 * 5


# Routes

get "/:user/:repo/pull/:number" do
  k = key params
  fn = redis.get k

  unless fn
    fn = state params
    redis.setex k, TTL, fn
  end

  send_file "images/#{fn}.png"
end


# Helpers

def key p
  "#{NS}:#{p[:user]}/#{p[:repo]}/#{p[:number]}"
end

def pull_request! p
  repo = "#{p[:user]}/#{p[:repo]}"
  Octokit.pull repo, p[:number]
end

def state p
  pull = pull_request! p
  if pull.merged_at
    "merged"

  elsif pull.closed_at
    "rejected"

  else
    "open"
  end
end```

Add last-modified header to response.
user
```ruby
#!/usr/bin/env ruby
# vim: et ts=2 sw=2

require "sinatra"
require "octokit"
require "redis"
require "json"

# Init

$redis = Redis.new
VERSION = %x{git show-ref --hash=7 --head HEAD}.strip
NAMESPACE = "pullstatus:#{VERSION}"
TTL = 60 * 5



# Routes

get "/:user/:repo/pull/:num" do
  pull_request = PullRequest.new params
  send_file "images/#{pull_request.status}.png",
    :last_modified=>pull_request.updated_at
end


# Models

class PullRequest
  def initialize params
    @user = params[:user]
    @repo = params[:repo]
    @num = params[:num]
  end

  def status
    if pull_request["merged_at"]
      "merged"

    elsif pull_request["closed_at"]
      "rejected"

    else
      "open"
    end
  end

  def method_missing meth, *args, &block
    pull_request[meth.to_s]
  end

  def pull_request
    @pr ||= get!
  end

  private

  def key
    "#{NAMESPACE}:#{repo}/#{@num}"
  end

  def repo
    "#{@user}/#{@repo}"
  end

  def get!
    json = $redis.get(key)

    if json.nil?
      json = fetch!.to_json
      $redis.setex key, TTL, json
    end

    JSON.parse(json)
  end

  def fetch!
    puts "Fetching: #{key} PUTS"
    Octokit.pull(repo, @num)
  end
end
```
assistant