class_docstr: Base density estimator.
docstr: Update the density model with a new set of features.
code: def update(
      self,
      features: dict[FeatureType, Tensor] | Tensor,
      group: Any = None,
  ):
      """Update the density model with a new set of features."""
      raise NotImplementedError
  
imports: from __future__ import annotations
  from abc import ABC, abstractmethod
  from typing import Any
  import torch
  from sklearn.mixture import GaussianMixture
  from torch import Tensor, nn
  from anomalib.models.ai_vad.features import FeatureType
  from anomalib.utils.metrics.min_max import MinMax
label_desc: Use image node_id 1 for calling the BaseDensityEstimator obj's underlying member method code with example usage: obj.update(features, group) without return types