_drawDatasets() {
    if (this.notifyPlugins('beforeDatasetsDraw', {cancelable: true}) === false) {
      return;
    }

    const metasets = this.getSortedVisibleDatasetMetas();
    for (let i = metasets.length - 1; i >= 0; --i) {
      this._drawDataset(metasets[i]);
    }

    this.notifyPlugins('afterDatasetsDraw');
  }
Draws all datasets unless a plugin returns `false` to the `beforeDatasetsDraw`
hook, in which case, plugins will not be called on `afterDatasetsDraw`.
@private