function sampler(arb, size) {
  size = typeof size === "number" ? Math.abs(size) : 10;
  return function (count) {
    if (typeof count === "number") {
      var acc = [];
      count = Math.abs(count);
      for (var i = 0; i < count; i++) {
        acc.push(arb.generator(size));
      }
      return acc;
    } else {
      return arb.generator(size);
    }
  };
}
- `sampler(arb: arbitrary a, genSize: nat = 10): (sampleSize: nat?) -> a`

      Create a sampler for a given arbitrary with an optional size. Handy when used in
      a REPL:
      ```
      > jsc = require('jsverify') // or require('./lib/jsverify') w/in the project
      ...
      > jsonSampler = jsc.sampler(jsc.json, 4)
      [Function]
      > jsonSampler()
      0.08467432763427496
      > jsonSampler()
      [ [ [] ] ]
      > jsonSampler()
      ''
      > sampledJson(2)
      [-0.4199344692751765, false]
      ```