/**
* Inserts an element into a pointer list before the specified element,
* which must be non null.
* @param list the pointer list to insert the new element into.
* @param element the list element before which the new element should
/**
* Inserts an element into a pointer list before the specified element,
* which must be non null.
* @param list the pointer list to insert the new element into.
* @param element the list element before which the new element should