code: def add(self, attendees):
          
          if attendees:
              if isinstance(attendees, str):
                  self.__attendees.append(
                      Attendee(address=attendees, event=self._event))
                  self._track_changes()
              elif isinstance(attendees, Attendee):
                  self.__attendees.append(attendees)
                  self._track_changes()
              elif isinstance(attendees, tuple):
                  name, address = attendees
                  if address:
                      self.__attendees.append(
                          Attendee(address=address, name=name, event=self._event))
                      self._track_changes()
              elif isinstance(attendees, list):
                  for attendee in attendees:
                      self.add(attendee)
              elif isinstance(attendees,
                              dict) and self._cloud_data_key in attendees:
                  attendees = attendees.get(self._cloud_data_key)
                  for attendee in attendees:
                      email = attendee.get(self._cc('emailAddress'), {})
                      address = email.get(self._cc('address'), None)
                      if address:
                          name = email.get(self._cc('name'), None)
                          # default value
                          attendee_type = attendee.get(self._cc('type'),
                                                       'required')
                          self.__attendees.append(
                              Attendee(address=address, name=name,
                                       attendee_type=attendee_type,
                                       event=self._event,
                                       response_status=
                                       ResponseStatus(parent=self,
                                                      response_status=
                                                      attendee.get(
                                                          self._cc('status'),
                                                          {}))))
              else:
                  raise ValueError('Attendees must be an address string, an '
                                   'Attendee instance, a (name, address) '
                                   'tuple or a list')
docs: Add attendees to the parent event
  
          :param attendees: list of attendees to add
          :type attendees: str or tuple(str, str) or Attendee or list[str] or
           list[tuple(str,str)] or list[Attendee]