Function: Checks if any filter has been registered for a hook.

Function: Calls the callback functions that have been added to a filter hook, specifying arguments in an array.

Function: Removes a callback function from a filter hook.

Function: Removes all of the callback functions from a filter hook.

Function: Retrieves the name of the current filter hook.

Function: Retrieves the name of the current action hook.

Function: Returns whether or not a filter hook is currently being processed.

Function: Returns whether or not an action hook is currently being processed.