+/** Execute some code (that does not return immediately) in kernel context
+ *
+ * This is very similar to simcall() right above, but the calling actor will not get rescheduled until
+ * actor->simcall_answer() is called explicitly.
+ *
+ * Since the return value does not come from the lambda directly, its type cannot be guessed automatically and must
+ * be provided as template parameter.
+ *
+ * This is meant for blocking actions. For example, locking a mutex is a blocking simcall.
+ * First it's a simcall because that's obviously a modification of the world. Then, that's a blocking simcall because if
+ * the mutex happens not to be free, the actor is added to a queue of actors in the mutex. Every mutex->unlock() takes
+ * the first actor from the queue, mark it as current owner of the mutex and call actor->simcall_answer() to mark that
+ * this mutex is now unblocked and ready to run again. If the mutex is initially free, the calling actor is unblocked
+ * right away with actor->simcall_answer() once the mutex is marked as locked.