toString(): string {
    // $FlowFixMe TODO
    const vals = this.iloc(0, 10).values;

    let valString = '';
    vals.forEach((v, idx) => {
      valString += `${this.index.get(idx)}\t${v}\n`;
    });

    return `${valString}Name: ${this.name}, dtype: ${this.dtype}`;
  }
Return the `Series` as a string

@returns {string}

@example
const ds = new Series([1, 2, 3, 4], {name: 'My test name', index: [2, 3, 4, 5]})
ds.toString()
// Returns:
// 2  1
// 3  2
// 4  3
// 5  4
// Name: My test name, dtype: dtype(int)