code: func (ms Mounts) mountDepth(i int) int {
  	ancestorCount := 0
  	current := ms[i]
  	for found := true; found; {
  		found = false
  		for _, mnt := range ms {
  			if mnt.ID == current.Parent {
  				ancestorCount++
  				current = mnt
  				found = true
  				break
  			}
  		}
  	}
  	return ancestorCount
  }
docs: // mountDepth determines and returns the number of ancestors of the mount at index i