code: def clear_past_metrics(self) -> None:
      del self._past_target_mean
  
file_path: autogluon/timeseries/tests/unittests/common.py
imports: import random
  from typing import Dict, List, Optional, Union
  import numpy
  import pandas
  from gluonts.dataset.common import ListDataset
  from autogluon.timeseries.dataset import TimeSeriesDataFrame
  from autogluon.timeseries.dataset.ts_dataframe import ITEMID, TIMESTAMP
  from autogluon.timeseries.metrics import TimeSeriesScorer
label_desc: Use image node_id 3 for calling the CustomMetric obj's underlying member method code with example usage: obj.clear_past_metrics() without return types