How to use the rope.base.change.ChangeSet function in rope

def _change_calls(self, call_changer, in_hierarchy=None, resources=None,
                      handle=taskhandle.NullTaskHandle()):
        if resources is None:
            resources = self.project.get_python_files()
        changes = ChangeSet('Changing signature of <%s>' % self.name)
        job_set = handle.create_jobset('Collecting Changes', len(resources))
        finder = occurrences.create_finder(
            self.project, self.name, self.pyname, instance=self.primary,
            in_hierarchy=in_hierarchy and self.is_method())
        if self.others:
            name, pyname = self.others
            constructor_finder = occurrences.create_finder(
                self.project, name, pyname, only_calls=True)
            finder = _MultipleFinders([finder, constructor_finder])
        for file in resources:
            job_set.started_job(file.path)
            change_calls = _ChangeCallsInModule(
                self.project, finder, file, call_changer)
            changed_file = change_calls.get_changed_module()
            if changed_file is not None:
                changes.add_change(ChangeContents(file, changed_file))

def _calculate_changes(self, dest, resources, task_handle):
        changes = ChangeSet('Moving module <%s>' % self.old_name)
        job_set = task_handle.create_jobset('Collecting changes',
                                            len(resources))
        for module in resources:
            job_set.started_job(module.path)
            if module == self.source:
                self._change_moving_module(changes, dest)
            else:
                source = self._change_occurrences_in_module(dest,
                                                            resource=module)
                if source is not None:
                    changes.add_change(ChangeContents(module, source))
            job_set.finished_job()
        if self.project == self.source.project:
            changes.add_change(MoveResource(self.source, dest.path))
        return changes

def _perform_change(self, change_, description):
        changes = rope.base.change.ChangeSet(description)
        changes.add_change(change_)
        self.project.do(changes)

def _basic_changes(self, changes):
        if isinstance(changes, change.ChangeSet):
            for child in changes.changes:
                for atom in self._basic_changes(child):
                    yield atom
        else:
            yield changes

def _calculate_changes(self, dest, resources, task_handle):
        changes = ChangeSet('Moving global <%s>' % self.old_name)
        job_set = task_handle.create_jobset('Collecting Changes',
                                            len(resources))
        for file_ in resources:
            job_set.started_job(file_.path)
            if file_ == self.source:
                changes.add_change(self._source_module_changes(dest))
            elif file_ == dest:
                changes.add_change(self._dest_module_changes(dest))
            elif self.tools.occurs_in_module(resource=file_):
                pymodule = self.project.get_pymodule(file_)
                # Changing occurrences
                placeholder = '__rope_renaming_%s_' % self.old_name
                source = self.tools.rename_in_module(placeholder,
                                                     resource=file_)
                should_import = source is not None
                # Removing out of date imports

def count_changes(change):
    """Counts the number of basic changes a `Change` will make"""
    if isinstance(change, ChangeSet):
        result = 0
        for child in change.changes:
            result += count_changes(child)
        return result
    return 1

def _get_moved_resources(self, changes, undo=False):
        result = {}
        if isinstance(changes, rope.base.change.ChangeSet):
            for change in changes.changes:
                result.update(self._get_moved_resources(change))
        if isinstance(changes, rope.base.change.MoveResource):
            result[changes.resource] = changes.new_resource
        if undo:
            return dict([(value, key) for key, value in result.items()])
        return result

def _get_moved_resources(self, changes, undo=False):
        result = {}
        if isinstance(changes, rope.base.change.ChangeSet):
            for change in changes.changes:
                result.update(self._get_moved_resources(change))
        if isinstance(changes, rope.base.change.MoveResource):
            result[changes.resource] = changes.new_resource
        if undo:
            return dict([(value, key) for key, value in result.items()])
        return result