code: def calc_anchors(self):
      raise NotImplementedError(
          "%s.calc_anchors is not available" % self.__class__.__name__
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import sys
  from ppdet.utils.logger import setup_logger
  from scipy.cluster.vq import kmeans
  import numpy
  from tqdm import tqdm
  from ppdet.utils.cli import ArgsParser
  from ppdet.utils.check import check_gpu, check_version, check_config
  from ppdet.core.workspace import load_config, merge_config
label_desc: Use image node_id 4 for calling the BaseAnchorCluster obj's underlying member method code with example usage: obj.calc_anchors() without return types