anchor.diff:  
   +aside-code("Example").
       from spacy.tokens import Doc
  -    Doc.set_extension('is_city', default=False)
  -    assert Doc.has_extension('is_city')
  +    Doc.set_extension('has_city', default=False)
  +    assert Doc.has_extension('has_city')
   
   +table(["Name", "Type", "Description"])
       +row
  
positive.code: 
  +aside-code("Example").
      from spacy.tokens import Doc
      Doc.set_extension('is_city', default=False)
      extension = Doc.get_extension('is_city')
      assert extension == (False, None, None, None)
  
  +table(["Name", "Type", "Description"])
  
negative.code:         +cell A flag indicating that the document has been syntactically parsed.
  
      +row
          +cell #[code is_sentenced]
          +cell bool
          +cell
              |  A flag indicating that sentence boundaries have been applied to
              |  the document.
  
      +row
          +cell #[code sentiment]
          +cell float
          +cell The document's positivity/negativity score, if available.
  