How to use Stream.concat?


I want to concatenate two streams of PointMeasurements, obtained by calling PointMeasurement.fetchObjStream. I investigated the APIs in the console but below is the closest I got to something that might work.
How can I do this?

s1 = Stream.ofInt(1,2,3)
s2 = Stream.ofInt(4,5,6)
14:10:53.686 a = Obj.arry()
14:10:53.692 [_type: {…}]
14:10:57.797 a.push(s1)
14:10:57.800 1
14:11:00.212 a
14:11:00.215 [C3.t…s.Stream, _type: {…}]
14:11:06.711 a.push(s2)
14:11:06.714 2
14:11:08.522 a
14:11:08.528 (2) [C3.t…s.Stream, C3.t…s.Stream, _type: {…}]
14:11:21.105 s12 = Stream.concat(a)
14:11:21.310 VM191373:1 POST 500 (Server Error)
(anonymous) @ VM191373:1
C3.client.sendRequest @ all.js...
14:11:21.313 all.js?env=browser&compat:570 Uncaught
C3.client.ActionError {name: "ActionError", message: "Invalid call; this obj value iterator only supports Depth-First traversal.", error: C3.t…s.Obj, stack: "Error: Invalid call; this obj value iterator only …77:20), <anonymous>:5:15)↵    at <anonymous>:1:14"}
error: C3.typesys.Obj
codes: ["NotClassified", _type: {…}]
debugInfo: [_empty: true, _type: {…}]
id: "3947.41374"
key: ""
parameters: [_empty: true, _type: {…}]
template: "Invalid call; this obj value iterator only supports Depth-First traversal."

PS. I would also need Stream.order as in the doc, but I get an error “Cannot find function order in object [object Stream<PointMeasurement>].”

PPS. On the server side, this code:

pmss = Stream.concat(ObjArry.fromArry([ppmss, pmss]));

throws an error: “Cannot convert object to Stream for concat argument streams: Incomplete type Stream to make.\nvalue: [InvalidInputParam]”