def defer(
            self,
            func: typing.Callable[[], typing.Any],
            until: typing.Union[int, float]=-1,
    ) -> typing.Any:
        """Defer the execution of a function until some clock value.

        Args:
            func (typing.Callable[[], typing.Any]): A callable that accepts no
                arguments. All return values are ignored.
            until (typing.Union[int, float]): A numeric value that represents
                the clock time when the callback becomes available for
                execution. Values that are less than the current time result in
                the function being called at the next opportunity.

        Returns:
            typing.Any: An opaque identifier that represents the callback
                uniquely within the processor. This identifier is used to
                modify the callback scheduling.

        Note:
            The time given should not be considered absolute. It represents
            the time when the callback becomes available to execute. It may
            be much later than the given time value when the function actually
            executes depending on the implementation.
        """
        raise NotImplementedError()