message: Remove unused functions from autofl.mnist_f.persistence
diff: -import glob
  -from typing import List
  -
  import numpy as np
  -def store_shards(shards: List[np.ndarray]):
  - for i, shard in enumerate(shards):
  - store(shard, fname="mnist_shard_" + str(i))
  -
  -
  -def load_shards(dir: str) -> List[np.ndarray]:
  - shards = []
  - for fname in glob.glob("mnist_shard_*.npy"):
  - shard = load(fname)
  - shards.append(shard)
  - return shards
  -
  -
  -def store(data: np.ndarray, fname: str) -> bool:
  - data[0][1][1][0] = 254
  +def store(data: np.ndarray, fname: str):
  np.save(fname, data)
  