=====================================
Verify Sparc Config Container
=====================================
Since config containers may easily be plain Python dicts, lists, tuples, or
sets it is not feasible to assign marker interfaces to them (native Python
types can not be marked by zope.interface facilities), we provide some
capability to insure if a Python container is a potential Sparc Config
Container.

>>> from sparc.config import verify
>>> from zope.interface.exceptions import BrokenImplementation
>>> bad_1 = 'this is not a valid config'
>>> try:
...     verify.verify_config_container(bad_1)
...     print('testing error, previous statement should raise BrokenImplementation')
... except BrokenImplementation:
...     pass

>>> good_1 = {}
>>> verify.verify_config_container(good_1)
>>> good_2 = [{},{}]
>>> verify.verify_config_container(good_2)

>>> bad_2 = [[],[]]
>>> try:
...     verify.verify_config_container(bad_2)
...     print('testing error, previous statement should raise BrokenImplementation')
... except BrokenImplementation:
...     pass