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

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))
            job_set.finished_job()
        return changes

if getter is None:
            getter = 'get_' + self.name
        if setter is None:
            setter = 'set_' + self.name
        renamer = GetterSetterRenameInModule(
            self.project, self.name, self.pyname, getter, setter)
        for file in resources:
            job_set.started_job(file.path)
            if file == self.resource:
                result = self._change_holding_module(changes, renamer,
                                                     getter, setter)
                changes.add_change(ChangeContents(self.resource, result))
            else:
                result = renamer.get_changed_module(file)
                if result is not None:
                    changes.add_change(ChangeContents(file, result))
            job_set.finished_job()
        return changes

job_set = handle.create_jobset('Collecting Changes', len(resources))
        finder = occurrences.create_finder(
            self.pycore, 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.pycore, name, pyname, only_calls=True)
            finder = _MultipleFinders([finder, constructor_finder])
        for file in resources:
            job_set.started_job(file.path)
            change_calls = _ChangeCallsInModule(
                self.pycore, finder, file, call_changer)
            changed_file = change_calls.get_changed_module()
            if changed_file is not None:
                changes.add_change(ChangeContents(file, changed_file))
            job_set.finished_job()
        return changes

def _change_moving_module(self, changes, dest):
        if not self.source.is_folder():
            pymodule = self.project.get_pymodule(self.source)
            source = self.import_tools.relatives_to_absolutes(pymodule)
            pymodule = self.tools.new_pymodule(pymodule, source)
            source = self._change_occurrences_in_module(dest, pymodule)
            source = self.tools.new_source(pymodule, source)
            if source != self.source.read():
                changes.add_change(ChangeContents(self.source, source))

source = pymodule.source_code
        if module_with_imports.imports:
            start = pymodule.lines.get_line_end(
                module_with_imports.imports[-1].end_line - 1)
            result = source[:start + 1] + '\n\n'
        else:
            result = ''
            start = -1
        result += moving + source[start + 1:]

        # Organizing imports
        source = result
        pymodule = self.pycore.get_string_module(source, dest)
        source = self.import_tools.organize_imports(pymodule, sort=False,
                                                    unused=False)
        return ChangeContents(dest, source)

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
                pymodule = self.tools.new_pymodule(pymodule, source)
                source = self.tools.remove_old_imports(pymodule)
                # Adding new import
                if should_import:
                    pymodule = self.tools.new_pymodule(pymodule, source)
                    source, imported = importutils.add_import(
                        self.pycore, pymodule, self._new_modname(dest), self.old_name)
                    source = source.replace(placeholder, imported)
                source = self.tools.new_source(pymodule, source)
                if source != file_.read():
                    changes.add_change(ChangeContents(file_, source))
            job_set.finished_job()
        return changes

def _change_moving_module(self, changes, dest):
        if not self.source.is_folder():
            pymodule = self.project.get_pymodule(self.source)
            source = self.import_tools.relatives_to_absolutes(pymodule)
            pymodule = self.tools.new_pymodule(pymodule, source)
            source = self._change_occurrences_in_module(dest, pymodule)
            source = self.tools.new_source(pymodule, source)
            if source != self.source.read():
                changes.add_change(ChangeContents(self.source, source))

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

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))
            job_set.finished_job()
        return changes