# Source code for fontTools.ufoLib.errors

    from __future__ import annotations

    class UFOLibError(Exception):
        pass

    class UnsupportedUFOFormat(UFOLibError):
        pass

    class GlifLibError(UFOLibError):
        """An error raised by glifLib.

        This class is a loose backport of PEP 678, adding a :attr:`.note`
        attribute that can hold additional context for errors encountered.

        It will be maintained until only Python 3.11-and-later are supported.
        """

        def _add_note(self, note: str) -> None:
            # Loose backport of PEP 678 until we only support Python 3.11+, used for
            # adding additional context to errors.
            # TODO: Replace with https://docs.python.org/3.11/library/exceptions.html#BaseException.add_note
            (message, *rest) = self.args
            self.args = ((message + "\n" + note), *rest)

    class UnsupportedGLIFFormat(GlifLibError):
        pass