is not found. */
extern struct frame_info *frame_find_by_id (struct frame_id id);
+/* Given a frame's ID, find the previous frame's ID. Returns null_frame_id
+ if the frame is not found. */
+extern struct frame_id get_prev_frame_id_by_id (struct frame_id id);
+
/* Base attributes of a frame: */
/* The frame's `resume' address. Where the program will resume in