def METHOD_NAME(
    self,
    file_paths: Iterable[StrPath],
    *,
    relative_to: Optional[StrPath] = None,
) -> None:
    """Add files to the hash.
    Args:
        file_paths: Paths of the files to add. The full path (or relative) is
            included when adding it to the hash. This is not resolved prior
            to use. It is used as-is unless another argument acts up it.
        relative_to: Optionally, convert the file_path to path relative to
            this one. It is recommended that both paths be absolute.
    """
    for fp in file_paths:
        self.add_file_name(fp, relative_to=relative_to)
        self.add_file(fp)
        # end of file contents; only necessary with multiple files
        self._hash.update("\0".encode())