def METHOD_NAME(self, slot, subindex, roi):
    if slot is self.fixAtCurrent:
        # If we're becoming UN-fixed, send out a big dirty notification
        if (
            self._fixed
            and not self.fixAtCurrent.value
            and self._fixed_dirty_roi
            and (self._fixed_dirty_roi[1] - self._fixed_dirty_roi[0] > 0).all()
        ):
            self.Output.setDirty(*self._fixed_dirty_roi)
            self._fixed_dirty_roi = None
        self._fixed = self.fixAtCurrent.value
    elif slot is self.Input:
        if self._fixed:
            # We can't propagate this downstream,
            #  but we need to remember that it was marked dirty.
            # Expand our dirty bounding box.
            self._expand_fixed_dirty_roi((roi.start, roi.stop))
        else:
            self.Output.setDirty(roi.start, roi.stop)