code: def caseinsensitive(cls):
      
      if not issubclass(cls, Enum):
          raise TypeError('caseinsensitive decorator can only be applied to subclasses of enum.Enum')
      enum_options = getattr(cls, PYCKSON_ENUM_OPTIONS, {})
      enum_options[ENUM_CASE_INSENSITIVE] = True
      setattr(cls, PYCKSON_ENUM_OPTIONS, enum_options)
      return cls
docs: Annotation function to set an Enum to be case insensitive on parsing