code: def unset_default_viewer(self, doctype):
      viewers = self.get_viewers()
      if doctype in viewers:
          del viewers[doctype]
  
file_path: jupytext/src/jupytext_config/labconfig.py
imports: import json
  import logging
  from pathlib import Path
label_desc: Use image node_id 8 for calling the LabConfig obj's underlying member method code with example usage: obj.unset_default_viewer(doctype) without return types