def assertTimeZoneIsNotNone(self, dt, msg=None):
        '''Fail unless ``dt`` has a non-null ``tzinfo`` attribute.

        Parameters
        ----------
        dt : datetime
        msg : str
            If not provided, the :mod:`marbles.mixins` or
            :mod:`unittest` standard message will be used.

        Raises
        ------
        TypeError
            If ``dt`` is not a datetime object.
        '''
        if not isinstance(dt, datetime):
            raise TypeError('First argument is not a datetime object')

        self.assertIsNotNone(dt.tzinfo, msg=msg)
Fail unless ``dt`` has a non-null ``tzinfo`` attribute.

        Parameters
        ----------
        dt : datetime
        msg : str
            If not provided, the :mod:`marbles.mixins` or
            :mod:`unittest` standard message will be used.

        Raises
        ------
        TypeError
            If ``dt`` is not a datetime object.