def diff(self, revisions, include_files=[], exclude_patterns=[],
             extra_args=[]):
        """Returns the diff for the given revision spec.

        If the revision spec is empty, this returns the diff of the current
        branch with respect to its parent. If a single revision is passed in,
        this returns the diff of the change introduced in that revision. If two
        revisions are passed in, this will do a diff between those two
        revisions.

        The summary and description are set if guessing is enabled.
        """
        exclude_patterns = normalize_patterns(exclude_patterns,
                                              self.get_repository_info().path)

        diff = self._get_range_diff(revisions['base'], revisions['tip'],
                                    include_files, exclude_patterns)

        if revisions in 'parent_base':
            parent_diff = self._get_range_diff(
                revisions['parent_base'], revisions['base'], include_files,
                exclude_patterns)
        else:
            parent_diff = None

        return {
            'diff': diff,
            'parent_diff': parent_diff,
        }
dataset/ETHPy150Open reviewboard/rbtools/rbtools/clients/bazaar.py/BazaarClient.diff/swapped operands of `in`