How to use the ephemeris.IonosphericData function in ephemeris

def add_RXM_SFRB(self, msg):
        '''add some RXM_SFRB subframe data'''
        ion = ephemeris.IonosphericData(msg)
        if ion.valid:
            if msg.svid in self.ionospheric:
                old_ion = self.ionospheric[msg.svid]
            else:
                old_ion = None
            self.ionospheric[msg.svid] = ion
            if old_ion is None or old_ion != ion:
                util.saveObject('ionospheric.dat', self.ionospheric)