class_docstr: A context manager used to implement TestCase.assertWarns* methods.
code: def __enter__(self):
      # The __warningregistry__'s need to be in a pristine state for tests
      # to work properly.
      # pylint: disable=invalid-name, attribute-defined-outside-init
      for v in sys.modules.values():
          if getattr(v, "__warningregistry__", None):
              v.__warningregistry__ = {}
      self.warnings_manager = warnings.catch_warnings(record=True)
      self.warnings = self.warnings_manager.__enter__()
      warnings.simplefilter("always", self.expected)
      return self
  
imports: from __future__ import print_function, division, absolute_import
  import random
  import copy
  import warnings
  import tempfile
  import shutil
  import re
  import sys
  import importlib
  import functools
  import numpy
  import six.moves
  import imgaug
  import imgaug.random
  import imgaug.parameters
  from imgaug.augmentables.kps import KeypointsOnImage
label_desc: Use image node_id 1 for calling the _AssertWarnsContext obj's underlying member method code with example usage: obj.__enter__() and returns: self