Function sequence

docs/tests/v2/es6/js/sanddance.js:92328–92330

(ival, start, stop, step)

}

function sequence(ival, start, stop, step) {
  return ival ? ival.range(start, stop, step) : undefined;
}

function timeSequence(unit, start, stop, step) {
  return sequence(timeInterval(unit), start, stop, step);