code: def test_broadcast_list_kv_pair():
      """list key-value pair push & pull"""
  
      def check_list_kv_pair(kv, key):
          ones = [mx.nd.ones(shape)] * len(key)
          out = [mx.nd.empty(shape)] * len(key)
          kv.broadcast(key, ones, out)
          for o in out:
              check_diff_to_scalar(o, 1)
          out_list = [[mx.nd.empty(shape)] * 2 for _ in range(len(key))]
          key_list = [k + k for k in key]
          kv.broadcast(key_list, ones, out_list)
          for o in out_list:
              for oo in o:
                  check_diff_to_scalar(oo, 1)
  
      check_list_kv_pair(init_kv(), keys)
      check_list_kv_pair(init_kv(), str_keys)
  
file_path: mxnet/tests/python/unittest/test_kvstore_custom.py
imports: import mxnet
  import numpy
  import unittest
  from mxnet.test_utils import rand_ndarray, assert_almost_equal
  from common import assertRaises
  from mxnet.base import py_str, MXNetError
label_desc: Use image node_id 4 for calling a global function with example usage: test_broadcast_list_kv_pair() without return types