code: def on_epoch_begin(self, epoch_idx, logs):
      self.container.reset()
  
imports: import torch
  from .utils import th_matrixcorr
  from .meters.averagemeter import AverageMeter
  from .callbacks import Callback
  from .losses import lovaszloss, hingeloss, dice_coeff
label_desc: Use image node_id 2 for calling the MetricCallback obj's underlying member method code with example usage: obj.on_epoch_begin(epoch_idx, logs) without return types