# Pastebin Fzshpyyv
class ProviderAPIs(object):

    __registry = {}

    __iter__ = __registry.__iter__
    __getitem__ = __registry.__getitem__

    def __init__(self):
        raise RuntimeError('`ProviderAPIs` class may not be instantiated.')

    @classmethod
    def __getattr__(cls, item):
        try:
            return cls.__registry[item]
        except KeyError:
            raise AttributeError("'ProviderAPIs' has no attribute %s" % item)

    @classmethod
    def _register_provider_api(cls, name, obj):
        """Register an instance of a class as a provider api"""
        if name in cls.__registry:
            raise DuplicateProviderError(
                '`%(name)s` has already been registered as an api '
                'provider by `%(prov)r`' % {'name': name,
                                            'prov': cls.__registry[name]})
        cls.__registry[name] = obj

    @classmethod
    def _clear_registry_instances(cls):
        """This is only to ever be used in testing."""
        cls.__registry.clear()


class DuplicateProviderError(Exception):
    """Attempting to register a duplicate API provider."""