code: def test_callstack2():
      with pytest.raises(ValueError) as excinfo:
          C.io.MinibatchSource(C.io.CTFDeserializer("", streams={}))
      assert "[CALL STACK]" in str(excinfo.value)
  
imports: import numpy
  import pytest
  import cntk
  from multiprocessing import Process, Queue
label_desc: Use image node_id 4 for calling a global function with example usage: test_callstack2() without return types