code: def test_summary_str(self):
      model = self.model
      self.assertTrue(isinstance(model.summary("str"), str))
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import absolute_import
  import unittest
  import turicreate
  import random
  import tempfile
  import math
  import numpy
  from numbers import Number
  from .None import util
  import pytest
  from turicreate.toolkits._internal_utils import _mac_ver
  from turicreate.toolkits._main import ToolkitError
  import uuid
label_desc: Use image node_id 15 for calling the ActivityClassifierTest obj's underlying member method code with example usage: obj.test_summary_str() without return types