<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def assert_angle(name, q):
 """ Check that ``q`` is an angular `~astropy.units.Quantity`. """

    if isinstance(q, u.Quantity):
        if q.unit.physical_type == 'angle':
            pass
        else:
            raise ValueError("{0} should have angular units".format(name))
    else:
        raise TypeError("{0} should be a Quantity instance".format(name))