code: function pick(obj){
    var keys = [].slice.call(arguments, 1);
    var ret = {};
  
    for (var i = 0, key; key = keys[i]; i++) {
      if (key in obj) ret[key] = obj[key];
    }
  
    return ret;
  }
docs: Pick keys from an `obj`.
  
  @param {Object} obj
  @param {Strings} keys...
  @return {Object}