code: def __str__(self):
      lines = [
          "",
          "[diff]",
          str(self.diffstat),
          "[left]",
          str(self.astat),
          "[right]",
          str(self.bstat),
      ]
      return "\n".join(lines)
  
imports: from nnabla.utils import nnabla_pb2
  from six.moves import filter
  import copy
  import nnabla
  import nnabla.ext_utils
  import nnabla.functions
  import nnabla.utils.converter
  import nnabla.dtypes
  from nnabla.testing import assert_allclose
  import numpy
  import numpy
  import platform
label_desc: Use image node_id 2 for calling the ArrayDiffStats obj's underlying member method code with example usage: obj.__str__() and returns: str