def fetch(self, num=None):
    if num:
      return self._dataset[:num]
    else:
      return self._dataset
Test the yz slice cutout
dataset/ETHPy150Open nikcub/floyd/floyd/db/__init__.py/Query.fetch--crossover with--dataset/ETHPy150Open neurodata/ndstore/test/test_probability.py/Test_Probability_Slice.test_yz