How to get/modify individually vertex position of imported face mesh object?

I'm using a custom face-mesh object exported from blender.
I can change/modify translation, scale, and rotation of the mesh as follows.
// @input SceneObject face_object


pos = new vec3(0,7,0)

scale = new vec3(2,2,2)


However, I couldn't find how to get/modify each vertex location in script.

MeshBuilder seems to be used for mesh generation.
How can I individually get or modify vertex location of the imported face-mesh object in script?

Thank you.