What does this traffic light mean?
Colors          Everywhere              In MA           To Boston drivers
green           look, then go           go              avoid looking and go
yellow          slow down               go              accelerate
red             stop                    stop            look, then go
flashing yellow procede slowly          go              go quickly
flashing red    yield, then procede     go              go slowly
flashing green  Huh?  Doesn't exist.    Almost never    go
                                        changes.  Go.
red&yellow      Huh?  Doesn't exist.    Pedestrian      look, then go
                                        crossing; stop.
flashing        Police car.             Police car;     slow down
red&blue                                pull over.