old_contents: from django.http import HttpResponse
  from google.appengine.ext import db
  import pickle
  
  class Chart(db.Model):
    key = db.StringProperty(required=True)
    data = db.BlogProperty()
  
  
  def index(request):
    return HttpResponse("Hello world!")
  
  
  def add(key, value):
    m = Chart().gql('WHERE key = :key', key=key)
  
new_contents: from django.http import HttpResponse
  from google.appengine.ext import db
  import pickle
  
  class Chart(db.Model):
    id = db.StringProperty(required=True)
    data = db.BlobProperty()
  
  
  def index(request):
    return HttpResponse("Hello world!")
  
  
  def add(key, value):
    m = Chart().gql('WHERE key = :key', key=key)
  
subject: fix 2 bugs