Load all the appointments from persistent storage

async def _load_all(self):
        '''
        Load all the appointments from persistent storage
        '''
        to_delete = []
        for iden, val in self._hivedict.items():
            try:
                appt = _Appt.unpack(val)
                if appt.iden != iden:
                    raise s_exc.InconsistentStorage(mesg='iden inconsistency')
                self._addappt(iden, appt)
                self._next_indx = max(self._next_indx, appt.indx + 1)
            except (s_exc.InconsistentStorage, s_exc.BadStorageVersion, s_exc.BadTime, TypeError, KeyError,
                    UnicodeDecodeError) as e:
                logger.warning('Invalid appointment %r found in storage: %r.  Removing.', iden, e)
                to_delete.append(iden)
                continue

        for iden in to_delete:
            await self._hivedict.pop(iden)

        # Make sure we don't assign the same index to 2 appointments
        if self.appts:
            maxindx = max(appt.indx for appt in self.appts.values())
            self._next_indx = maxindx + 1