class_docstr: Default filter. Subclass this class or use the `simplefilter`
  decorator to create own filters.
code: def filter(self, lexer, stream):
      raise NotImplementedError()
  
file_path: catboost/contrib/python/Pygments/py3/pygments/filter.py
label_desc: Use image node_id 2 for calling the Filter obj's underlying member method code with example usage: obj.filter(lexer, stream) without return types