code: function pluck() {
  	    var properties = [];
  	    for (var _i = 0; _i < arguments.length; _i++) {
  	        properties[_i - 0] = arguments[_i];
  	    }
  	    var length = properties.length;
  	    if (length === 0) {
  	        throw new Error('list of properties cannot be empty.');
  	    }
  	    return map_1.map.call(this, plucker(properties, length));
  	}
docs: Maps each source value (an object) to its specified nested property.
  
  <span class="informal">Like {@link map}, but meant only for picking one of
  the nested properties of every emitted object.</span>
  
  <img src="./img/pluck.png" width="100%">
  
  Given a list of strings describing a path to an object property, retrieves
  the value of a specified nested property from all values in the source
  Observable. If a property can't be resolved, it will return `undefined` for
  that value.
  
  @example <caption>Map every every click to the tagName of the clicked target element</caption>
  var clicks = Rx.Observable.fromEvent(document, 'click');
  var tagNames = clicks.pluck('target', 'tagName');
  tagNames.subscribe(x => console.log(x));
  
  @see {@link map}
  
  @param {...string} properties The nested properties to pluck from each source
  value (an object).
  @return {Observable} Returns a new Observable of property values from the
  source values.
  @method pluck
  @owner Observable