People shuffled forward in suits and saris, stilettos and sweatpants, pushing strollers or carrying neck pillows or briefcases or teddy bears or shopping bags festooned with two-dimensional bows and holly. Sometimes only one passport would be stamped; other times you heard two or three or four stamped in quick succession—like library books, once upon a time. And the overall rhythm of people advancing and stamps stamping had a kind of prolonged regularity to it, like a jazz improvisation that, for all its deviations, never loses its beat.