Function: Returns a comma-separated string or array of functions that have been called to get to the current point in code.

Function: Retrieves IDs that are not already present in the cache.

Function: Tests if the current device has the capability to upload files.

Function: Tests if a given path is a stream URL

Function: Returns an empty array.

Function: Returns null.

Function: Returns an empty string.

Function: Strips close comment and close php tags from file headers used by WP.

Function: Permanently deletes comments or posts of any type that have held a status of ‘trash’ for the number of days defined in EMPTY_TRASH_DAYS.