def parse_gist
      src = content.strip
      if src =~ /\A\w+(\-\w+)*\/\d+/
        src = "https://gist.github.com/#{src}"
      else
        src.sub! /\A(?=gist\.github\.com)/, 'https://'
      end
      src.sub!(/((?<!\.js)|\.git)$/, '.js')
      %Q|<script src="#{src}"></script>|
    end
def parse_gist
      src = content.strip
      if src =~ /\A\w+(\-\w+)*\/\d+/
        src = "https://gist.github.com/#{src}"
      else
        src.sub! /\A(?=gist\.github\.com)/, 'https://'
      end
      src.sub!(/((?<!\.js)|\.git)$/, '.js')
      %Q|<script src="#{src}"></script>|
    end
embed gist, accepts:
 |
   luikore/737238
   gist.github.com/luikore/737238
   https://gist.github.com/luikore/737238