google app engine(GAE)のデータストアについて

from google.appengine.ext import webapp
from google.appengine.ext import db
from google.appengine.ext.webapp.util import run_wsgi_app

class DS(db.Model):
  mozi = db.StringProperty()
  suuji = db.IntegerProperty()
 
class main(webapp.RequestHandler):
  def get(self):
  #保存方法
    ds = DS()
    ds.IDE = 'last'
    ds.suuji = 3
    ds.put()
  
  #読み出し方法
    grts = db.GqlQuery('SELECT * FROM DS')
    for grt in grts:
      self.response.out.write(grt.mozi)
      self.response.out.write(grt.suuji)
   
   
application = webapp.WSGIApplication([('/',main)],debug=True)

def main():
  run_wsgi_app(application)
 
if __name__ == "__main__":
  main()