class_docstr: All Feature classes extend this class to implement custom visualizations in
  Insights.
  
  It enforces child classes to implement ``visualization_type`` and ``visualize``
  methods.
class_docstr_tok: ["All","Feature","classes","extend","this","class","to","implement","custom","visualizations","in","Insights",".","It","enforces","child","classes","to","implement","``","visualization_type","``","and","``","visualize","``","methods","."]
code: def visualization_type() -> str:
      raise NotImplementedError
  
imports: import base64
  import warnings
  from collections import namedtuple
  from io import BytesIO
  from typing import Callable, List, Optional, Union
  from captum._utils.common import safe_div
  from captum.attr._utils import visualization
  from captum.insights.attr_vis._utils.transforms import format_transforms
label_desc: Use image node_id 2 for calling the BaseFeature obj's underlying member method code with example usage: obj.visualization_type() without return types