How to use the taskgraph.optimize.IndexSearch function in taskgraph

aliases['toolchain-{}'.format(alias)] = \
                        t.task['metadata']['name']

            for b in from_build:
                user_value = b

                if not b.startswith('toolchain-'):
                    b = 'toolchain-{}'.format(b)

                task = toolchains.get(aliases.get(b, b))
                if not task:
                    self.log(logging.ERROR, 'artifact', {'build': user_value},
                             'Could not find a toolchain build named `{build}`')
                    return 1

                task_id = IndexSearch().should_replace_task(
                    task, {}, task.optimization.get('index-search', []))
                artifact_name = task.attributes.get('toolchain-artifact')
                if task_id in (True, False) or not artifact_name:
                    self.log(logging.ERROR, 'artifact', {'build': user_value},
                             'Could not find artifacts for a toolchain build '
                             'named `{build}`. Local commits and other changes '
                             'in your checkout may cause this error. Try '
                             'updating to a fresh checkout of mozilla-central '
                             'to use artifact builds.')
                    return 1

                record = ArtifactRecord(task_id, artifact_name)
                records[record.filename] = record

        # Handle the list of files of the form path@task-id on the command
        # line. Each of those give a path to an artifact to download.