code: def test_get_padding_lengths(self):
      list_field = ListField([self.field1, self.field2, self.field3])
      list_field.index(self.vocab)
      lengths = list_field.get_padding_lengths()
      assert lengths == {"num_fields": 3, "list_num_tokens": 5}
  
file_path: magnitude/pymagnitude/third_party/allennlp/tests/data/fields/list_field_test.py
imports: from __future__ import absolute_import
  from __future__ import print_function
  import numpy
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data import Token, Vocabulary
  from allennlp.data.fields import TextField, LabelField, ListField, IndexField, SequenceLabelField
  from allennlp.data.token_indexers import SingleIdTokenIndexer, TokenCharactersIndexer
label_desc: Use image node_id 2 for calling the TestListField obj's underlying member method code with example usage: obj.test_get_padding_lengths() without return types