func (st *State) CurrentFrame() *frame.Frame {
	x, err := st.frames.Top()
	if err != nil {
		return nil
	}
	return x.(*frame.Frame)
}
func (st *State) CurrentFrame() *frame.Frame {
	x, err := st.frames.Top()
	if err != nil {
		return nil
	}
	return x.(*frame.Frame)
}
// CurrentFrame returns the frame currently at the top of the frame stack