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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fetch(cls, id, service=None, endpoint=None, *args, **kwargs):
 """Customize fetch because it lives on a special endpoint."""

        if service is None and endpoint is None:
            raise InvalidArguments(service, endpoint)

        if endpoint is None:
            sid = service['id'] if isinstance(service, Entity) else service
            endpoint = 'services/{0}/integrations'.format(sid)

        return getattr(Entity, 'fetch').__func__(cls, id, endpoint=endpoint,
                                                 *args, **kwargs)