def items_count(self):
        return self._item_ids.size
train a grammar using an annotated mali.
dataset/ETHPy150Open muricoca/crab/scikits/crab/models/classes.py/MatrixBooleanPrefDataModel.items_count--crossover with--dataset/ETHPy150Open CGATOxford/cgat/obsolete/xrate_blocks.py/trainOnMali