old_contents: __all__ = ['all_warnings']
  
  from contextlib import contextmanager
  import sys
  import warnings
  import inspect
  
  @contextmanager
  def all_warnings():
      """
      Context for use in testing to ensure that all warnings are raised.
  
      Examples
      --------
      >>> import warnings
      >>> def foo():
      ...     warnings.warn(RuntimeWarning("bar"))
  
      We raise the warning once, while the warning filter is set to "once".
      Hereafter, the warning is invisible, even with custom filters:
  
      >>> with warnings.catch_warnings():
      ...     warnings.simplefilter('once')
      ...     foo()
  
      We can now run ``foo()`` without a warning being raised:
  
      >>> from numpy.testing import assert_warns
      >>> foo()
  
      To catch the warning, we call in the help of ``all_warnings``:
  
      >>> with all_warnings():
      ...     assert_warns(RuntimeWarning, foo)
      """
  
      # Whenever a warning is triggered, Python adds a __warningregistry__
      # member to the *calling* module.  The exercize here is to find
      # and eradicate all those breadcrumbs that were left lying around.
      #
      # We proceed by first searching all parent calling frames and explicitly
      # clearing their warning registries (necessary for the doctests above to
      # pass).  Then, we search for all submodules of skimage and clear theirs
      # as well (necessary for the skimage test suite to pass).
  
      frame = inspect.currentframe()
      if frame:
          for f in inspect.getouterframes(frame):
              f[0].f_locals['__warningregistry__'] = {}
      del frame
  
      for mod in list(sys.modules.values()):
          try:
              mod.__warningregistry__.clear()
          except AttributeError:
              pass
  
      with warnings.catch_warnings(record=True) as w:
          warnings.simplefilter("always")
          yield w
  
new_contents: __all__ = ['all_warnings']
  
  from contextlib import contextmanager
  import sys
  import warnings
  import inspect
  
  
  @contextmanager
  def all_warnings():
      """
      Context for use in testing to ensure that all warnings are raised.
  
      Examples
      --------
      >>> import warnings
      >>> def foo():
      ...     warnings.warn(RuntimeWarning("bar"))
  
      We raise the warning once, while the warning filter is set to "once".
      Hereafter, the warning is invisible, even with custom filters:
  
      >>> with warnings.catch_warnings():
      ...     warnings.simplefilter('once')
      ...     foo()
  
      We can now run ``foo()`` without a warning being raised:
  
      >>> from numpy.testing import assert_warns
      >>> foo()
  
      To catch the warning, we call in the help of ``all_warnings``:
  
      >>> with all_warnings():
      ...     assert_warns(RuntimeWarning, foo)
      """
  
      # Whenever a warning is triggered, Python adds a __warningregistry__
      # member to the *calling* module.  The exercize here is to find
      # and eradicate all those breadcrumbs that were left lying around.
      #
      # We proceed by first searching all parent calling frames and explicitly
      # clearing their warning registries (necessary for the doctests above to
      # pass).  Then, we search for all submodules of skimage and clear theirs
      # as well (necessary for the skimage test suite to pass).
  
      frame = inspect.currentframe()
      if frame:
          for f in inspect.getouterframes(frame):
              f[0].f_locals['__warningregistry__'] = {}
      del frame
  
      for mod in list(sys.modules.values()):
          try:
              mod.__warningregistry__.clear()
          except AttributeError:
              pass
  
      with warnings.catch_warnings(record=True) as w:
          warnings.simplefilter("always")
          yield w
  
subject: Add some PEP8