analytics.js
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;
}
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;
}
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 ; }
Pick keys from an `obj`.

@param {Object} obj
@param {Strings} keys...
@return {Object}
Pick keys from an obj .