code: function pick(obj, var_keys){
          var keys = typeof arguments[1] !== 'string'? arguments[1] : slice(arguments, 1),
              out = {},
              i = 0, key;
          while (key = keys[i++]) {
              out[key] = obj[key];
          }
          return out;
      }
docs: Return a copy of the object, filtered to only have values for the whitelisted keys.