docs: def read_git_commit_timestamp_for_file(filepath, repo_path=None):
      """Obtain the timestamp for the most recent commit to a given file in a
      Git repository.
  
      Parameters
      ----------
      filepath : `str`
          Repository-relative path for a file.
      repo_path : `str`, optional
          Path to the Git repository. Leave as `None` to use the current working
          directory.
  
      Returns
      -------
      commit_timestamp : `datetime.datetime`
          The datetime of a the most recent commit to the given file.
  
      Raises
      ------
      IOError
          Raised if the ``filepath`` does not exist in the Git repository.
      """
      repo = git.repo.base.Repo(path=repo_path, search_parent_directories=True)
      head_commit = repo.head.commit
  
      # most recent commit datetime of the given file
      for commit in head_commit.iter_parents(filepath):
          return commit.committed_datetime
  
      # Only get here if git could not find the file path in the history
      raise IOError('File {} not found'.format(filepath))