gistfile1.rb

require 'rubygems'
require 'sinatra'
require 'rack/contrib'
 
class MyApp < Sinatra::Default
  get '/' do
    'main app!'
  end
end
 
use Rack::Callbacks do
  # before {'before'}
  run MyApp
  # after  {'after'}
end

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ERROR: !! Unexpected error while processing request: wrong number of arguments (1 for 0)