str, err := client.Permission.LookupEntityStream(context.Background(), &v1.PermissionLookupEntityRequest{
    Metadata: &v1.PermissionLookupEntityRequestMetadata{
        SnapToken: "",
        SchemaVersion: "",
        Depth: 50,
    },
    EntityType: "document",
    Permission: "view",
    Subject: &v1.Subject{
        Type: "user",
        Id: "1",
    },
    PageSize: 20,
    ContinuousToken: "",
})

// handle stream response
for {
    res, err := str.Recv()

    if err == io.EOF {
        break
    }

    // res.EntityId
}

{
  "result": {
    "entity_id": "<string>",
    "continuous_token": "<string>"
  },
  "error": {
    "code": 123,
    "message": "<string>",
    "details": [
      {
        "@type": "<string>"
      }
    ]
  }
}