'This handler retrieves a given bucket\'s signing context from the cache
and adds it into the request context.'

def redirect_from_cache(self, params, context, **kwargs):

    bucket = params.get('Bucket')
    signing_context = self._cache.get(bucket)
    if (signing_context is not None):
        context['signing'] = signing_context
    else:
        context['signing'] = {'bucket': bucket}
