class LocationEvent(Event):
    """
    ...
    Attributes
    ----------
    ...
    modifiers : frozenset
        The keyboard modifiers currently being pressed (except for KeyEvent).
    """
    ...
    def __init__(self, ..., *, modifiers=None):
        ...
        self.modifiers = frozenset(modifiers if modifiers is not None else [])
        ...

class LocationEvent(Event):
    ...  # some attributes, but not `modifiers`
    def __init__(self, ..., *, modifiers: Iterable[str] | None = ...) -> None: ...