How to use the @grafana/runtime.getDataSourceSrv function in @grafana/runtime

const queries = request.targets.filter(t => {
      return t.datasource !== MIXED_DATASOURCE_NAME;
    });

    if (!queries.length) {
      return of({ data: [] } as DataQueryResponse); // nothing
    }

    // Build groups of queries to run in parallel
    const sets: { [key: string]: DataQuery[] } = groupBy(queries, 'datasource');
    const mixed: BatchedQueries[] = [];
    for (const key in sets) {
      const targets = sets[key];
      const dsName = targets[0].datasource;
      mixed.push({
        datasource: getDataSourceSrv().get(dsName),
        targets,
      });
    }
    return this.batchQueries(mixed, request);
  }

const queries = request.targets.filter(t => {
      return t.datasource !== MIXED_DATASOURCE_NAME;
    });

    if (!queries.length) {
      return of({ data: [] } as DataQueryResponse); // nothing
    }

    // Build groups of queries to run in parallel
    const sets: { [key: string]: DataQuery[] } = groupBy(queries, 'datasource');
    const mixed: BatchedQueries[] = [];
    for (const key in sets) {
      const targets = sets[key];
      const dsName = targets[0].datasource;
      mixed.push({
        datasource: getDataSourceSrv().get(dsName),
        targets,
      });
    }
    return this.batchQueries(mixed, request);
  }

});
      return;
    }

    this.panelCtrl = scope.$$childHead.ctrl;
    const loader = getAngularLoader();
    const template = '';

    const scopeProps = { ctrl: this.panelCtrl };

    this.component = loader.load(this.element, scopeProps, template);

    const validatonMessage = await getAlertingValidationMessage(
      panel.transformations,
      panel.targets,
      getDataSourceSrv(),
      panel.datasource
    );

    if (validatonMessage) {
      this.setState({ validatonMessage });
    }
  }

});
      return;
    }

    this.panelCtrl = scope.$$childHead.ctrl;
    const loader = getAngularLoader();
    const template = '';

    const scopeProps = { ctrl: this.panelCtrl };

    this.component = loader.load(this.element, scopeProps, template);

    const validatonMessage = await getAlertingValidationMessage(
      panel.transformations,
      panel.targets,
      getDataSourceSrv(),
      panel.datasource
    );

    if (validatonMessage) {
      this.setState({ validatonMessage });
    }
  }

export function getDatasourceSrv(): DatasourceSrv {
  return getDataSourceService() as DatasourceSrv;
}