code: def test_handle_unseen_none(self):
      vocab = self.get_vocab()
      tags = [
          list(set(random.choices(vocab, k=random.randint(1, 3))))
          for i in range(10)
      ]
      tags.append(None)
  
      train_tags = tags[:-1]
      test_tags = tags[-1:]
  
      enc = MultiHotEncoder()
      enc.prepare(train_tags)
  
      encoded_data = enc.encode(test_tags)
      decoded_data = enc.decode(encoded_data)
      assert (np.array(encoded_data[0]) == 0).all()
      assert decoded_data[0] == []
  
file_path: lightwood/tests/unit_tests/encoder/categorical/test_multihot.py
imports: import unittest
  import numpy
  import random
  import string
  from sklearn.metrics import accuracy_score
  from lightwood.encoder.categorical.multihot import MultiHotEncoder
label_desc: Use image node_id 4 for calling the TestMultiHotEncoder obj's underlying member method code with example usage: obj.test_handle_unseen_none() without return types