Override default ``*range=`` handler to account for relative computation.

def indxByRange(self, valu):
        '''
        Override default ``*range=`` handler to account for relative computation.
        '''

        if not isinstance(valu, (list, tuple)):
            raise s_exc.BadCmprValu(valu=valu, cmpr='*range=')

        if len(valu) != 2:
            raise s_exc.BadCmprValu(valu=valu, cmpr='*range=')

        tick, tock = self.getTickTock(valu)

        if tick > tock:
            # User input has requested a nullset
            return ()

        return self._indxTimeRange(tick, tock)