code: def get_momentum(self, epoch=None):
      if epoch is None:
          epoch = self.last_epoch + 1
      return self.lmbd(epoch)
  
imports: import numpy
  import matplotlib.pyplot
  from mpl_toolkits.mplot3d import Axes3D
  import random
  import torch
  import torch.nn
  import torch.nn.functional
  import os
  from collections import abc
label_desc: Use image node_id 3 for calling the BNMomentumScheduler obj's underlying member method code with example usage: obj.get_momentum(epoch) and returns: self