    # File lib/merb-core/controller/mime.rb, line 70
        def add_mime_type(key, transform_method, mimes, new_response_headers = {}, default_quality = 1, &block)
          enforce!(key => Symbol, mimes => Array)

          content_type = new_response_headers["Content-Type"] || mimes.first

          if charset = new_response_headers.delete(:charset)
            content_type += "; charset=#{charset}"
          end

          ResponderMixin::TYPES.update(key =>
            {:accepts           => mimes,
             :transform_method  => transform_method,
             :content_type      => content_type,
             :response_headers  => new_response_headers,
             :default_quality   => default_quality,
             :response_block    => block })

          mimes.each do |mime|
            ResponderMixin::MIMES.update(mime => key)
          end

          Merb::RenderMixin.class_eval "def render_\#{key}(thing = nil, opts = {})\nself.content_type = :\#{key}\nrender thing, opts\nend\n", __FILE__, __LINE__

          nil
        end