code: def diff(self, other=diff.Diffable.Index, paths=None, create_patch=False, **kwargs):
          
          # index against index is always empty
          if other is self.Index:
              return diff.DiffIndex()
  
          # index against anything but None is a reverse diff with the respective
          # item. Handle existing -R flags properly. Transform strings to the object
          # so that we can call diff on it
          if isinstance(other, string_types):
              other = self.repo.rev_parse(other)
          # END object conversion
  
          if isinstance(other, Object):
              # invert the existing R flag
              cur_val = kwargs.get('R', False)
              kwargs['R'] = not cur_val
              return other.diff(self.Index, paths, create_patch, **kwargs)
          # END diff against other item handling
  
          # if other is not None here, something is wrong
          if other is not None:
              raise ValueError("other must be None, Diffable.Index, a Tree or Commit, was %r" % other)
  
          # diff against working copy - can be handled by superclass natively
          return super(IndexFile, self).diff(other, paths, create_patch, **kwargs)
docs: Diff this index against the working copy or a Tree or Commit object
  
          For a documentation of the parameters and return values, see
          Diffable.diff
  
          :note:
              Will only work with indices that represent the default git index as
              they have not been initialized with a stream.