code: def test_str_special_method():
      codec = NdarrayCodec()
      assert str(codec) == "NdarrayCodec()"
  
      codec = CompressedNdarrayCodec()
      assert str(codec) == "CompressedNdarrayCodec()"
  
imports: import numpy
  import pytest
  from petastorm.codecs import NdarrayCodec, CompressedNdarrayCodec
  from petastorm.unischema import UnischemaField
label_desc: Use image node_id 2 for calling a global function with example usage: test_str_special_method() without return types