I have this datastore model

```
class Project(db.Model)
projectname = db.StringProperty()
projecturl = db.StringProperty()

class Task(db.Model)
project = db.ReferenceProperty(Project)
taskname= db.StringProperty()
taskdesc = db.StringProperty()

```

How do I edit the value of taskname ? say I have task1 and i want to change it to task1-project