code: def get_decoder_mask(self_attn_inputs):
      """Returns causal mask to apply for self-attention layer.
  
      Args:
        self_attn_inputs: Inputs to self attention layer to determine mask shape
      """
      len_s = tf.shape(self_attn_inputs)[1]
      bs = tf.shape(self_attn_inputs)[:1]
      mask = K.cumsum(tf.eye(len_s, batch_shape=bs), 1)
      return mask
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import gc
  import json
  import os
  import shutil
  import data_formatters.base
  import libs.utils
  import numpy
  import pandas
  import tensorflow
label_desc: Use image node_id 6 for calling a global function with example usage: get_decoder_mask(_attn_inputs) and returns: mask