code: def test_assign_none_without_allow_none_resets_to_default_value(self):
      class Example2(HasTraits):
          color1 = UseEnum(Color, allow_none=False)
          color2 = UseEnum(Color)
  
      example = Example2()
      example.color1 = None
      example.color2 = None
      self.assertIs(example.color1, Color.red)
      self.assertIs(example.color2, Color.red)
  
imports: import enum
  import unittest
  from traitlets import CaselessStrEnum, Enum, FuzzyEnum, HasTraits, TraitError, UseEnum
label_desc: Use image node_id 15 for calling the TestUseEnum obj's underlying member method code with example usage: obj.test_assign_none_without_allow_none_resets_to_default_value() without return types