a method for constructing a labDT from a python datetime with timezone info
        
        :param python_datetime: datetime object with timezone info
        :return: labDT object

def fromPython(cls, python_datetime):

        ''' a method for constructing a labDT from a python datetime with timezone info
        
        :param python_datetime: datetime object with timezone info
        :return: labDT object
        '''

    # validate inputs
        title = 'Python datetime input for labDT.fromPython'
        if not isinstance(python_datetime, datetime):
            raise TypeError('\n%s must be a valid %s object.' % (title, datetime.__class__))
        elif not python_datetime.tzinfo:
            raise ValueError('\n%s must have a timezone.' % title)

    # construct labDT from python datetime
        dT = python_datetime.astimezone(pytz.utc)
        dt_kwargs = {
            'year': dT.year,
            'month': dT.month,
            'day': dT.day,
            'hour': dT.hour,
            'minute': dT.minute,
            'second': dT.second,
            'microsecond': dT.microsecond,
            'tzinfo': dT.tzinfo
        }
        return labDT(**dt_kwargs)