register

# File actionpack/lib/action_dispatch/http/mime_type.rb, line 159
      def register(string, symbol, mime_type_synonyms = [], extension_synonyms = [], skip_lookup = false)
        new_mime = Type.new(string, symbol, mime_type_synonyms)

        SET << new_mime

        ([string] + mime_type_synonyms).each { |str| LOOKUP[str] = new_mime } unless skip_lookup
        ([symbol] + extension_synonyms).each { |ext| EXTENSION_LOOKUP[ext.to_s] = new_mime }

        @register_callbacks.each do |callback|
          callback.call(new_mime)
        end
        new_mime
      end