Returns a copy of this chart with updated series names.
|ui.Chart||The ui.Chart instance.|
|Dictionary|Dictionary||New series names. If it's a string, the name of the series at seriesIndex is set to seriesNames. If it's a list, the value at index i in the list is used as a label for series number i. If it's a dictionary or an object, it's treated as a map from existing series names to new series names. In the last two cases, seriesIndex is ignored.|
|Number, optional||The index of the series to rename. Ignored if seriesNames is a list or dictionary. Series are 0-indexed.|