docs: function merge(from, to) {
    assert.ok(from);
    assert.equal(typeof (from), 'object');
    assert.ok(to);
    assert.equal(typeof (to), 'object');
  
    var keys = Object.getOwnPropertyNames(from);
    keys.forEach(function (key) {
      if (to[key])
        return;
  
      var value = Object.getOwnPropertyDescriptor(from, key);
      Object.defineProperty(to, key, value);
    });
  
    return to;
  }