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: header_dos_protection.rb
    path of file: ./repos/brakeman/test/apps/rails3.2/config/initializers
    
    the code of the file until where you have to start completion: # https://groups.google.com/d/msg/ruby-security-ann/A-ebV4WxzKg/KNPTbX8XAQUJ
ActiveSupp
    
      def get(details) 
        if details[:formats] 
          details = details.dup 
          syms    = Set.new Mime::SET.symbols 
          details[:formats] = details[:formats].select { |v| 
            syms.include? v 
          } 
        end 