class User(GPNode):
    node_data = {
        'name': '',
        'last_name': '',
    }

# Use the model:
me = User(last_name='Doe')
me.set_name('Mike')
me.get_name()         # Mike
me.get_last_name()    # Doe
try:
    me.get_foo()      # throws exception
except: 
    me.get('foo')     # this is fine, returns None
me.set('foo', 'bar')  # it's fine to use non-declared data
me.get('foo')         # bar
me.save()

# retrieve it from db:
me = User.get_by_id(123)