      {'default': None},
      {'method': lambda: None}])
  def test_underscore_accepts_valid(valid_kwargs):
      doc = Doc(Vocab(), words=['hello', 'world'])
      doc.set_extension('test', **valid_kwargs, force=True)
 
</s> remove         doc.set_extension('test', **invalid_kwargs, force=True)
 </s> add         doc.set_extension('test', **invalid_kwargs)
    doc.set_extension('test', **valid_kwargs)
      {'default': None},
      {'method': lambda: None}])
  def test_underscore_accepts_valid(valid_kwargs):
      doc = Doc(Vocab(), words=['hello', 'world'])
    doc.set_extension('test', **valid_kwargs)
keep keep keep keep replace
 Fix tests for Python 2 
spacy/tests/test_underscore.py