code: def _normalize_by_total(freq):
      """Helper function to normalize a frequency distribution."""
      total = sum(freq.values())
      return {
          k: round(v / (total + EPSILON), 2) for k, v in freq.items()
      }
  
imports: from multiprocessing import Pool
  from typing import Optional, Any, Dict, Tuple, Union, List, TYPE_CHECKING, TypeVar, DefaultDict
  import numpy
  import collections
  from cleanlab.internal.constants import MAX_CLASS_TO_SHOW, ALPHA, EPSILON, TINY_VALUE
  from cleanlab.object_detection.filter import _filter_by_class, _calculate_true_positives_false_positives
  from cleanlab.object_detection.rank import _get_valid_inputs_for_compute_scores, _separate_prediction, _separate_label, _get_prediction_type
  from cleanlab.internal.object_detection_utils import bbox_xyxy_to_xywh
label_desc: Use image node_id 12 for calling a global function with example usage: _normalize_by_total(freq) and returns: unknown