'Retrieves the quotas for specific resources.
A helper method which retrieves the quotas for the specific
resources identified by keys, and which apply to the current
context.
:param context: The request context, for access checks.
:param tenant_id: the tenant_id to check quota.
:param resources: A dictionary of the registered resources.'

def _get_quotas(self, context, tenant_id, resources):

    quotas = DbQuotaDriver.get_tenant_quotas(context, resources, tenant_id)
    return dict(((k, v) for (k, v) in quotas.items()))
