You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: puma.rb
    path of file: ./repos/puma/lib/rack/handler
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

# This module is used as an 'include' file in code at bottom of file
module Puma
  module
    
    def config(app, options = {})
      require_relative '../../puma'
      require_relative '../../puma/configuration'
      require_relative '../../puma/log_writer'
      require_relative '../../puma/launcher'

      default_options = DEFAULT_OPTIONS.dup

      # Libraries pass in values such as :Port and there is no way to determine
      # if it is a default provided by the library or a special value provided
      # by the user. A special key `user_supplied_options` can be passed. This
      # contains an array of all explicitly defined user options. We then
      # know that all other values are defaults
      if user_supplied_options = options.delete(:user_supplied_options)
        (options.keys - user_supplied_options).each do |k|
          default_options[k] = options.delete(k)
        end
      end