class_docstr: ``BaseBackend`` is the base class for all backends.
  All explainability implementations should extend this abstract class
  and implement the methods marked as abstract.
code: def run_explainer(self, x: pd.DataFrame) -> dict:
      raise NotImplementedError(
          f"`{self.__class__.__name__}` is a subclass of BaseBackend and "
          f"must implement the `_run_explainer` method"
      )
  
file_path: shapash/shapash/backend/base_backend.py
imports: from abc import ABC, abstractmethod
  from typing import Any, List, Optional, Union
  import pandas
  import numpy
  from shapash.utils.check import check_model, check_contribution_object
  from shapash.utils.transform import adapt_contributions, get_preprocessing_mapping
  from shapash.utils.utils import choose_state
label_desc: Use image node_id 2 for calling the BaseBackend obj's underlying member method code with example usage: obj.run_explainer(x) without return types