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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def serialize(self, obj):
 # type: ignore # type: (Any) -> Union[Dict[str, Any], List, Tuple, str, int, float, None] """Builds a serialized object. * If obj is None, return None. * If obj is str, int, long, float, bool, return directly. * If obj is datetime.datetime, datetime.date convert to string in iso8601 format. * If obj is list, serialize each element in the list. * If obj is dict, return the dict with serialized values. * If obj is ask sdk model, return the dict with keys resolved from the union of model's ``attribute_map`` and ``deserialized_types`` and values serialized based on ``deserialized_types``. * If obj is a generic class instance, return the dict with keys from instance's ``deserialized_types`` and values serialized based on ``deserialized_types``. :param obj: The data to serialize. :type obj: object :return: The serialized form of data. :rtype: Union[Dict[str, Any], List, Tuple, str, int, float, None] """

        if obj is None:
            return None
        elif isinstance(obj, self.PRIMITIVE_TYPES):
            return obj
        elif isinstance(obj, list):
            return [self.serialize(sub_obj) for sub_obj in obj]
        elif isinstance(obj, tuple):
            return tuple(self.serialize(sub_obj) for sub_obj in obj)
        elif isinstance(obj, (datetime, date)):
            return obj.isoformat()
        elif isinstance(obj, Enum):
            return obj.value
        elif isinstance(obj, decimal.Decimal):
            if obj % 1 == 0:
                return int(obj)
            else:
                return float(obj)

        if isinstance(obj, dict):
            obj_dict = obj
        else:
            # Convert model obj to dict
            # All the non null attributes under `deserialized_types`
            # map are considered for serialization.
            # The `attribute_map` provides the key names to be used
            # in the dict. In case of missing `attribute_map` mapping,
            # the original attribute name is retained as the key name.
            class_attribute_map = getattr(obj, 'attribute_map', {})
            class_attribute_map.update(
                {
                    k: k for k in obj.deserialized_types.keys()
                    if k not in class_attribute_map
                }
            )

            obj_dict = {
                class_attribute_map[attr]: getattr(obj, attr)
                for attr, _ in iteritems(obj.deserialized_types)
                if getattr(obj, attr) is not None
            }

        return {key: self.serialize(val) for key, val in iteritems(obj_dict)}