Your snippet is missing some key contextual info from the surrounding code: where was edg created and what does it refer to? Lacking that, it is impossible to guess what face=edg.faces[0] returns, hence what pushpull is acting on.
I found it, it was a test .rb file, not a plugin but it did have
def get_from_excel
That is where the plugin was getting the code from.
Thank you,
The style does change now that I am in the correct code.