/**
 * @param {number} start
 * @param {number=} stop
 * @param {number=} step
 */
d3.range = function(start, stop, step) {
  if (arguments.length < 3) {
    step = 1;
    if (arguments.length < 2) {
      stop = start;
      start = 0;
    }
  }
  if ((stop - start) / step == Infinity) throw new Error("infinite range");
  var range = [],
       i = -1,
       j;
  if (step < 0) while ((j = start + step * ++i) > stop) range.push(j);
  else while ((j = start + step * ++i) < stop) range.push(j);
  return range;
};