code: def initialize_accuracy_calculator(self):
      if self.accuracy_calculator is None:
          self.accuracy_calculator = AccuracyCalculator()
  
imports: from collections import defaultdict
  import torch
  import tqdm
  from ..utils import common_functions
  from ..utils import inference
  from ..utils.accuracy_calculator import AccuracyCalculator
label_desc: Use image node_id 3 for calling the BaseTester obj's underlying member method code with example usage: obj.initialize_accuracy_calculator() without return types