-(** [trace nid round d t msg] records a the message [msg] together with the a node preorder
- [nid], the [round], the [d]one set and the [t]odo set *)
+(** [trace nid round d t msg] records the message [msg] together
+ with the a node preorder [nid], the [round], the [d]one set and
+ the [t]odo set *)