text: import unittest
  
  import torch
  
  from fastNLP import Vocabulary, DataSet, Instance
  from fastNLP.embeddings import LSTMCharEmbedding, CNNCharEmbedding, StackEmbedding
  
  
  class TestCharEmbed(unittest.TestCase):
      def test_case_1(self):
          ds = DataSet([Instance(words=['hello', 'world']), Instance(words=['hello', 'Jack'])])
          vocab = Vocabulary().from_dataset(ds, field_name='words')
          self.assertEqual(len(vocab), 5)
          cnn_embed = CNNCharEmbedding(vocab, embed_size=60)
          lstm_embed = LSTMCharEmbedding(vocab, embed_size=70)
          embed = StackEmbedding([cnn_embed, lstm_embed])
          x = torch.LongTensor([[2, 1, 0], [4, 3, 4]])
          y = embed(x)
          self.assertEqual(tuple(y.size()), (2, 3, 130))
  
  