function generateTuple(gens) {
  var len = gens.length;
  var result = generatorBless(function (size) {
    var r = [];
    for (var i = 0; i < len; i++) {
      r[i] = gens[i](size);
    }
    return r;
  });

  return utils.curried2(result, arguments);
}
- `generator.tuple(gens: (generator a, generator b...)): generator (a, b...)`