code: def get_asset_ids(self):
          
          if not self.is_asset_based_activity():
              raise IllegalState()
          else:
              ids = []
              for i in self._my_map['assetIds']:
                  ids.append(Id(i))
              return IdList(ids)
docs: Gets the Ids of any assets associated with this activity.
  
          return: (osid.id.IdList) - list of asset Ids
          raise:  IllegalState - is_asset_based_activity() is false
          compliance: mandatory - This method must be implemented.