code: def str_updater(key, recv, local):
      """use updater: += with str keys"""
      if isinstance(key, bytes):
          key = py_str(key)
      assert isinstance(key, str)
      local += recv
  
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
  import pytest
label_desc: Use image node_id 12 for calling a global function with example usage: str_updater(key, recv, local) without return types