def METHOD_NAME(self, obj):
    """
    This method is needed to support proper serialization. While its name is value_to_string()
    the real meaning of the method is to convert the value to some serializable format.
    Since most of the enum values are strings or integers we WILL NOT convert it to string
    to enable integers to be serialized natively.
    """
    if django.VERSION >= (2, 0):
        value = self.value_from_object(obj)
    else:
        value = self._get_val_from_obj(obj)
    return value.value if value else None