NameError: name 'vector_angle_between' is not defined

[JasonHanJC]

Hi,

I am trying to use cut_mesh blender add-on to fill the hole on my mesh. But When choose res_mode as Maximum, I got the error said 'vector_angle_between' is not defined. I am using Blender 2.78c on my Windows 10 machine.

If you have any idea, please tell me. Thank you.