Finds the slack bus, adds a Generator with the appropriate data
        and sets the bus type to slack.

def push_slack(self, tokens):
        """ Finds the slack bus, adds a Generator with the appropriate data
        and sets the bus type to slack.
        """
        logger.debug("Pushing slack data: %s" % tokens)

        bus = self.case.buses[tokens["bus_no"] - 1]

        g = Generator(bus)
        g.q_max = tokens["q_max"]
        g.q_min = tokens["q_min"]
        # Optional parameter
#        if tokens.has_key("status"):
#        g.online = tokens["status"]

        self.case.generators.append(g)

        bus.type = "ref"