set index(index: Immutable.List | Array<number | string>) {
    this.set_axis(0, parseIndex(index, this.values));
  }
Set the index of the `Series`, an `Immutable.List`

@param {List|Array} index
   The next values for the index of the `Series`

@example
const ds = new Series([1.5, 2, 3], {name: 'Series name'});
ds.index = [1, 2, 3];

// Returns List [1, 2, 3]
ds.index;