class_docstr: Produces a sequence of MNIST digits with labels.
code: def __getitem__(self, idx):
      batch_x = self.images[
          idx * self.batch_size : (idx + 1) * self.batch_size
      ]
      batch_y = self.labels[
          idx * self.batch_size : (idx + 1) * self.batch_size
      ]
      return batch_x, batch_y
  
imports: import os
  import warnings
  from absl import app
  from absl import flags
  import matplotlib
  from matplotlib import figure
  from matplotlib.backends import backend_agg
  import numpy
  import tensorflow.compat.v2
  import tensorflow_probability
  from tensorflow_probability.python.internal import tf_keras
label_desc: Use image node_id 5 for calling the MNISTSequence obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: batch_x,  batch_y