docstr: Get sampled class centers and their momentum.
  
  Parameters
  ----------
  index: NDArray
      Local index for memory bank to sample, start from 0 to num_local.
code: def get(self, index):
      """
      Get sampled class centers and their momentum.
  
      Parameters
      ----------
      index: NDArray
          Local index for memory bank to sample, start from 0 to num_local.
      """
      return self.weight[index], self.weight_mom[index]
  
file_path: insightface/recognition/partial_fc/mxnet/memory_bank.py
imports: import os
  import numpy
  from mxnet import nd
  import mxnet
  from memory_samplers import WeightIndexSampler
label_desc: Use image node_id 3 for calling the MemoryBank obj's underlying member method code with example usage: obj.get(index) and returns: self,  self