class_docstr: A model for testing batched predictions with a minibatch size of 3.
code: def max_minibatch_size(self):
      return 3
  
imports: from absl.testing import absltest
  from absl.testing import parameterized
  from lit_nlp.api import dataset
  from lit_nlp.api import model
  from lit_nlp.api import types
label_desc: Use image node_id 3 for calling the _BatchingTestModel obj's underlying member method code with example usage: obj.max_minibatch_size() and returns: int