# File lib/www/mechanize/file_response.rb, line 31
      def [](key)
        return nil unless key.downcase == 'content-type'
        return 'text/html' if directory?
        return 'text/html' if ['.html', '.xhtml'].any? { |extn|
          @file_path =~ /#{extn}$/
        }
        nil
      end