gistfile1.js

function range() {
  switch (arguments.length) {
  case 1:
    var start=0, stop=arguments[0], step=1;
    break;
  case 2:
    var start=arguments[0], stop=arguments[1], step=1;
    break;
  case 3:
    var start=arguments[0], stop=arguments[1], step=arguments[2];
    break;
  }

  return function() {
    if (start < stop) {
      var current = start;
      start += step;
      return current;
    };
  };
};