async def load_artifact(
      self,
      *,
      app_name: str,
      user_id: str,
      session_id: str,
      filename: str,
      version: Optional[int] = None,
  ) -> Optional[types.Part]:
    """Gets an artifact from the artifact service storage.

    The artifact is a file identified by the app name, user ID, session ID, and
    filename.

    Args:
      app_name: The app name.
      user_id: The user ID.
      session_id: The session ID.
      filename: The filename of the artifact.
      version: The version of the artifact. If None, the latest version will be
        returned.

    Returns:
      The artifact or None if not found.
    """
Gets an artifact from the artifact service storage.

    The artifact is a file identified by the app name, user ID, session ID, and
    filename.

    Args:
      app_name: The app name.
      user_id: The user ID.
      session_id: The session ID.
      filename: The filename of the artifact.
      version: The version of the artifact. If None, the latest version will be
        returned.

    Returns:
      The artifact or None if not found.
    
src/google/adk/artifacts/base_artifact_service.py