code: def test_qa_conv_single():
      out = qa(
          qa_example["q2_conv"],
          qa_example["c"],
          prev_qa=[(qa_example["q1"], qa_example["a1"])],
      )
      assert type(out) == str, "Qa answer not a string"
      assert (
          out == qa_example["a2"]
      ), "Wrong answer to simple conversational qa"
  
imports: from backprop import Emotion, ImageClassification, QA, Summarisation, TextClassification, TextGeneration, TextVectorisation
  import numpy
  import torch
  import os
label_desc: Use image node_id 5 for calling a global function with example usage: test_qa_conv_single() without return types