iloc(startVal: number, endVal: ?number): Series | number | string {
    if (typeof endVal === 'undefined')
      return this.values.get(startVal);

    const {name} = this.kwargs;
    const index = this.index.slice(startVal, endVal);

    return new Series(this.values.slice(startVal, endVal), {name, index});
  }
Return the Series between [startVal, endVal), or at startVal if endVal is undefined

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

@param {int} startVal
@param {int} [endVal]

@returns {Series|number|string}

@example
const ds = new Series([1, 2, 3, 4], {name: 'New Series'})
ds.iloc(1)      // 2
ds.iloc(1, 3)   // Series([2, 3], {name: 'New Series', index: [1, 2]})