sort_values(ascending: boolean = true): Series {
    const sortedIndex = ascending
      ? this.index.sort(this._sort_ascending)
      : this.index.sort(this._sort_descending);

    return new Series(sortedIndex.map(i => this.iloc(i)), {name: this.name, index: sortedIndex});
  }
Return a sorted `Series` in either ascending or descending order

pandas equivalent: [Series.sort_values](http://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.sort_values.html)

@param {boolean} ascending
   Sort in ascending (true) or descending (false) order

@returns {Series}

@example
const ds = new Series([2, 1, 0, 3], {name: 'New Series', index: [0, 1, 2, 3]})

ds.sort_values(true)    // Series([0, 1, 2, 3], {name: 'New Series', index: [2, 1, 0, 3]})
ds.sort_values(false)   // Series([3, 2, 1, 0], {name: 'New Series', index: [3, 0, 1, 2]})