code: def _getphoto_url(self,pid,size='n'):
          
          p=self._getphoto_information(pid)
          farm=p['farm']
          server=p['server']
          secret=p['secret']
          url="http://farm%s.staticflickr.com/%s/%s_%s_%s.jpg"\
              %(farm,server,pid,secret,size)
  
          return url
docs: Returns URL to photo, optionally can link
          to different size images
          Size suffixes according to:
          http://www.flickr.com/services/api/misc.urls.html
  
          s   small square 75x75
          q   large square 150x150
          t   thumbnail, 100 on longest side
          m   small, 240 on longest side
          n   small, 320 on longest side
          -   medium, 500 on longest side
          z   medium 640, 640 on longest side
          c   medium 800, 800 on longest side
          b   large, 1024 on longest side*
          o   original image, either a jpg, gif or png, depending on source format