code: def deserializer(json_data, widget):
      return DataInstance(
          memoryview(json_data["data"]).tobytes() if json_data else None
      )
  
imports: import pytest
  from traitlets import Bool, Tuple, List, Instance, CFloat, CInt, Float, Int, TraitError, observe
  from .utils import setup, teardown
  import ipywidgets
  from ipywidgets import Widget
label_desc: Use image node_id 5 for calling a global function with example usage: deserializer(json_data, widget) and returns: DataInstance