code: function _catch(selector) {
  	    var operator = new CatchOperator(selector);
  	    var caught = this.lift(operator);
  	    return (operator.caught = caught);
  	}
docs: Catches errors on the observable to be handled by returning a new observable or throwing an error.
  @param {function} selector a function that takes as arguments `err`, which is the error, and `caught`, which
  is the source observable, in case you'd like to "retry" that observable by returning it again. Whatever observable
  is returned by the `selector` will be used to continue the observable chain.
  @return {Observable} an observable that originates from either the source or the observable returned by the
  catch `selector` function.
  @method catch
  @owner Observable