render() {
    return (
      <XYPlot onMouseLeave={this._onMouseLeave} width={300} height={300}>
        <VerticalGridLines />
        <HorizontalGridLines />
        <XAxis />
        <YAxis />
        <LineSeries onNearestX={this._onNearestX} data={DATA[0]} />
        <LineSeries data={DATA[1]} />
        <Crosshair
          values={this.state.crosshairValues}
          className={'test-class-name'}
        />
      </XYPlot>
    );
  }
Event handler for onNearestX.
@param {Object} value Selected value.
@param {index} index Index of the value in the data array.
@private