@classmethod
    def from_dict(cls, d, return_obj=None):
        if not d:
            return None
        if return_obj is None:
            return_obj = cls()

        return_obj.start_time = DateTimeWithPrecision.from_dict(d.get('start_time'))
        return_obj.end_time = DateTimeWithPrecision.from_dict(d.get('end_time'))
        
        return return_obj


# NOT AN ACTUAL STIX TYPE
dataset/ETHPy150Open STIXProject/python-stix/stix/indicator/valid_time.py/ValidTime.from_dict/original