as a concrete example, if you had this schema:

definition user {}

definition document {
  relation admin: user
  relation writer: user
  relation viewer: user

  permission write = admin + writer
  permission view = viewer + write
}

calling

Expand

on

document:somedocument

and

view

, will return a tree containing all users who are in relations

viewer

,

writer

and

admin

, since all three form

view