code: def test_binary(base_model_context):
      test_data = [{"instances": [{"b64": "YQ=="}]}]
  
      envelope = JSONEnvelope(
          lambda x, y: [row.decode("utf-8") for row in x]
      )
      results = envelope.handle(test_data, base_model_context)
      assert results == ['{"predictions": ["a"]}']
  
file_path: serve/ts/torch_handler/unit_tests/test_envelopes.py
imports: import pytest
  from ts.torch_handler.base_handler import BaseHandler
  from ts.torch_handler.request_envelope.body import BodyEnvelope
  from ts.torch_handler.request_envelope.json import JSONEnvelope
label_desc: Use image node_id 6 for calling a global function with example usage: test_binary(base_model_context) without return types