code: def test_sub_split_to_proto(self):
      sp = self._builder.info.splits["train[75%:]"].to_proto()
      self.assertEqual("train[75%:]", sp.name)
      self.assertEqual([5], sp.shard_lengths)
  
imports: from tensorflow_datasets import testing
  from tensorflow_datasets.core import naming
  from tensorflow_datasets.core import proto
  from tensorflow_datasets.core import splits
  from tensorflow_datasets.core.utils import shard_utils
  import tensorflow_datasets.public_api
label_desc: Use image node_id 6 for calling the SplitsTest obj's underlying member method code with example usage: obj.test_sub_split_to_proto() without return types