Why does face.followme delete the face? How to get the result faces of followme?

Developers Ruby API
1

I used followme method like this:

face.followme(edges)

Then the face was deleted. How can I get the result entities of the followme method?

2 
ents_before = Sketchup.active_model.active_entities.to_a
face.followme(edges)
#How can I get the result entities of the followme method?
ents_added = Sketchup.active_model.active_entities.to_a - ents_before
#How to get the result faces of followme?
result_faces = ents_added.grep(Sketchup::Face)