def init_serials(self, ses_seed):
        """
        Generate unique seeds for each rupture with numpy.arange.
        This should be called only in event based calculators
        """
        sources = self.get_sources()
        serial = ses_seed
        for src in sources:
            nr = src.num_ruptures
            src.serial = serial
            serial += nr
Generate unique seeds for each rupture with numpy.arange.
        This should be called only in event based calculators