def slave_changed(interface='slave'):
    for rid in relation_ids(interface):
        for unit in related_units(rid):
            rdata = relation_get(unit=unit, rid=rid)
            if rdata.get('leader'):
                if rdata.get('master_address') is not get_slave_status():
                    slave_departed()
                    slave_joined()
def slave_changed(interface='slave'):
    for rid in relation_ids(interface):
        for unit in related_units(rid):
            rdata = relation_get(unit=unit, rid=rid)
            if rdata.get('leader'):
                if rdata.get('master_address') is not get_slave_status():
                    slave_departed()
                    slave_joined()