docs: def resend_invitations(self):
      """
      Resends invites for an event.  ::
  
          event = service.calendar().get_event(id='KEY HERE')
          event.resend_invitations()
  
      Anybody who has not declined this meeting will get a new invite.
      """
  
      if not self.id:
        raise TypeError(u"You can't send invites for an event that hasn't been created yet.")
  
      # Under the hood, this is just an .update() but with no attributes changed.
      # We're going to enforce that by checking if there are any changed attributes and bail if there are
      if self._dirty_attributes:
        raise ValueError(u"There are unsaved changes to this invite - please update it first: %r" % self._dirty_attributes)
  
      self.refresh_change_key()
      body = soap_request.update_item(self, [], calendar_item_update_operation_type=u'SendOnlyToAll')
      self.service.send(body)
  
      return self