def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def update(dt=0):
  global projpts, rgb, depth
  depth,_ = freenect.sync_get_depth()
  rgb,_ = freenect.sync_get_video()
  q = depth
  X,Y = np.meshgrid(range(640),range(480))
  # YOU CAN CHANGE THIS AND RERUN THE PROGRAM!
  # Point cloud downsampling
  d = 4
  projpts = calibkinect.depth2xyzuv(q[::d,::d],X[::d,::d],Y[::d,::d])
  refresh()