+Note [LoopBreaker OccInfo]
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+An OccInfo of (IAmLoopBreaker False) is used by the occurrence
+analyser in two ways:
+ (a) to mark loop-breakers in a group of recursive
+ definitions (hence the name)
+ (b) to mark binders that must not be inlined in this phase
+ (perhaps it has a NOINLINE pragma)
+Things with (IAmLoopBreaker False) do not get an unfolding
+pinned on to them, so they are completely opaque.
+
+See OccurAnal Note [Weak loop breakers] for (IAmLoopBreaker True).
+