Returns a construct for an array of bus data.

def _get_bus_array_construct(self):
        """ Returns a construct for an array of bus data.
        """
        bus_no = integer.setResultsName("bus_no")
        v_base = real.setResultsName("v_base") # kV
        v_magnitude = Optional(real).setResultsName("v_magnitude")
        v_angle = Optional(real).setResultsName("v_angle") # radians
        area = Optional(integer).setResultsName("area") # not used yet
        region = Optional(integer).setResultsName("region") # not used yet

        bus_data = bus_no + v_base + v_magnitude + v_angle + \
            area + region + scolon

        bus_data.setParseAction(self.push_bus)

        bus_array = Literal("Bus.con") + "=" + "[" + "..." + \
            ZeroOrMore(bus_data + Optional("]" + scolon))

        # Sort buses according to their name (bus_no)
        bus_array.setParseAction(self.sort_buses)

        return bus_array