class_docstr: A mock Comm object.
  
  Can be used to inspect calls to Comm's open/send/close methods.
code: def close(self, *args, **kwargs):
      self.log_close.append((args, kwargs))
  
file_path: vegafusion/python/vegafusion-jupyter/tests/conftest.py
imports: import pytest
  from ipykernel.comm import Comm
  from ipywidgets import Widget
label_desc: Use image node_id 4 for calling the MockComm obj's underlying member method code with example usage: obj.close() without return types