How to use the @ngtools/webpack/src/transformers.getFirstNode function in @ngtools/webpack

const bootstrapPropAccessExpr = bootstrapCallExpr.expression as ts.PropertyAccessExpression;

            if (bootstrapPropAccessExpr.name.text !== 'bootstrapModule'
                || bootstrapPropAccessExpr.expression.kind !== ts.SyntaxKind.CallExpression) {
                return;
            }

            const nsPlatformCallExpr = bootstrapPropAccessExpr.expression as ts.CallExpression;
            if (!(getExpressionName(nsPlatformCallExpr.expression) === 'platformNativeScriptDynamic')) {
                return;
            }

            const idPlatformNativeScript = ts.createUniqueName('__NgCli_bootstrap_1');
            const idNgFactory = ts.createUniqueName('__NgCli_bootstrap_2');

            const firstNode = getFirstNode(sourceFile);

            // Add the transform operations.
            // TODO: if (ivy)
            const factoryClassName = entryModule.className; // + 'NgFactory';
            const factoryModulePath = normalizedEntryModulePath; // + '.ngfactory';


            const newBootstrapPropAccessExpr = ts.getMutableClone(bootstrapPropAccessExpr);
            const newNsPlatformCallExpr = ts.getMutableClone(bootstrapPropAccessExpr.expression) as ts.CallExpression;
            newNsPlatformCallExpr.expression = ts.createPropertyAccess(idPlatformNativeScript, 'platformNativeScript');
            newBootstrapPropAccessExpr.expression = newNsPlatformCallExpr;
            // TODO: if (ivy)
            // newBootstrapPropAccessExpr.name = ts.createIdentifier("bootstrapModuleFactory");
            newBootstrapPropAccessExpr.name = ts.createIdentifier("bootstrapModule");

            const newBootstrapCallExpr = ts.getMutableClone(bootstrapCallExpr);

const standardTransform: StandardTransform = (sourceFile: ts.SourceFile) => {
    const ops: TransformOperation[] = [];

    if (options.main === sourceFile.fileName) {
      const firstNode = getFirstNode(sourceFile);

      ops.push(
        ...insertAllImport(sourceFile, 'reflect-metadata', firstNode, true),
        ...insertAllImport(
          sourceFile,
          'zone.js/dist/zone-node',
          firstNode,
          true,
        ),
      );
    }

    return ops;
  };