code: def test_transform_1(self):
      transformer = LowercaseTransformer()
      s = "ĐI HỌC"
      output = transformer.transform(s)
      self.assertEqual("đi học", output)
  
imports: from unittest import TestCase
  from underthesea.feature_engineering.lowercase import LowercaseTransformer
label_desc: Use image node_id 1 for calling the TestUnicodeTransformer obj's underlying member method code with example usage: obj.test_transform_1() without return types