docs: def initialize_repository(path, spor_dir='.spor'):
      """Initialize a spor repository in `path` if one doesn't already exist.
  
      Args:
          path: Path to any file or directory within the repository.
          spor_dir: The name of the directory containing spor data.
  
      Returns: A `Repository` instance.
  
      Raises:
          ValueError: A repository already exists at `path`.
      """
      path = pathlib.Path(path)
      spor_path = path / spor_dir
      if spor_path.exists():
          raise ValueError('spor directory already exists: {}'.format(spor_path))
      spor_path.mkdir()
  
      return Repository(path, spor_dir)