How to get embeded value's path via Go API?

[micnncim]

In the following file, I want to get the path of the embeded value #A.#B.

#A: {
  #B
}

#B: {
  x: string
  y: string
}

I can get #A.x and #A.y via some functions of cuelang.org/go/cue but couldn't find a way to get #A.#B.