* @param array $checkKeys List of check keys to apply to all $keys. May also apply "check"
* keys to specific cache keys only by using cache keys as keys in the $checkKeys array.
* @param float[] &$asOfs Map of (key => UNIX timestamp of cached value; null on failure)
* @param array $checkKeys List of check keys to apply to all $keys. May also apply "check"
* keys to specific cache keys only by using cache keys as keys in the $checkKeys array.
* @param float[] &$asOfs Map of (key => UNIX timestamp of cached value; null on failure)