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: extensions.rb
    path of file: ./repos/truffleruby/bench/asciidoctor/asciidoctor/lib/asciidoctor
    
    the code of the file until where you have to start completion: # encoding: UTF-8
module Asciidoctor
# Exte
    
    def initialize name = nil, config = {}
      super config
      @name = name || @config[:name]
      # assign fallbacks
      case @config[:contexts]
      when ::NilClass
        @config[:contexts] ||= [:open, :paragraph].to_set
      when ::Symbol
        @config[:contexts] = [@config[:contexts]].to_set
      else
        @config[:contexts] = @config[:contexts].to_set
      end