@events = $session->getExplainedBy($object, $event[, $onehop ]);
The getExplainedBy() function is the inverse of the getExplains() function.
It returns those problems (or events) which the MODEL developer has listed as explaining this event.
The $onehop parameter is optional:
If it is omitted or passed as FALSE, the full list of problems that explain $event, whether directly or indirectly, is returned.
If it is passed as TRUE, only those problems that directly list $event among the events they explain are returned.
The function returns an array of array references with the format:
[ [ <classname::instancename>,<problemname> ], [ <classname::instancename>,<problemname> ], ... ]