re-emerge. This includes beams that meet a ball on the first rank
of the arena.
-\b A beam with a ball to its front-left square gets deflected 90 degrees
- to the right.
+\b A beam with a ball in its front-left square and no ball ahead of it
+ gets deflected 90 degrees to the right.
-\b A beam with a ball to its front-right square gets similarly deflected
- to the left.
+\b A beam with a ball in its front-right square and no ball ahead of
+ it gets similarly deflected to the left.
\b A beam that would re-emerge from its entry location is considered to be
\q{reflected}.