How to use the @uifabric/example-data.TestImages.iconPpt function in @uifabric/example-data

public render(): JSX.Element {
    const previewProps: IDocumentCardPreviewProps = {
      previewImages: [
        {
          name: 'Revenue stream proposal fiscal year 2016 version02.pptx',
          linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreview,
          iconSrc: TestImages.iconPpt,
          imageFit: ImageFit.cover,
          width: 318,
          height: 196
        }
      ]
    };

    return (

target: '_blank'
          },
          previewImageSrc: TestImages.documentPreview,
          iconSrc: TestImages.iconPpt,
          imageFit: ImageFit.cover,
          width: 318,
          height: 196
        },
        {
          name: 'Notes from Ignite conference',
          linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreviewTwo,
          iconSrc: TestImages.iconPpt,
          imageFit: ImageFit.cover,
          width: 318,
          height: 196
        },
        {
          name: 'FY17 Cost Projections',
          linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreviewThree,
          iconSrc: TestImages.iconPpt,
          imageFit: ImageFit.cover,
          width: 318,
          height: 196
        }

linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreviewTwo,
          iconSrc: TestImages.iconPpt,
          width: 144
        },
        {
          name: 'Spec Sheet for design',
          linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreviewThree,
          iconSrc: TestImages.iconPpt,
          width: 144
        },
        {
          name: 'Contoso Marketing Presentation',
          linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreview,
          iconSrc: TestImages.iconPpt,
          width: 144
        }
      ]
    };

    const theme = getTheme();

public render(): JSX.Element {
    const previewProps: IDocumentCardPreviewProps = {
      getOverflowDocumentCountText: (overflowCount: number) => `+${overflowCount} more`,
      previewImages: [
        {
          name: '2016 Conference Presentation',
          linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreview,
          iconSrc: TestImages.iconPpt,
          imageFit: ImageFit.cover,
          width: 318,
          height: 196
        },
        {
          name: 'New Contoso Collaboration for Conference Presentation Draft',
          linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreviewTwo,
          iconSrc: TestImages.iconPpt,
          imageFit: ImageFit.cover,
          width: 318,
          height: 196
        },

public render(): JSX.Element {
    const previewProps: IDocumentCardPreviewProps = {
      getOverflowDocumentCountText: (overflowCount: number) => `+${overflowCount} more`,
      previewImages: [
        {
          name: 'Revenue stream proposal fiscal year 2016 version02.pptx',
          linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreview,
          iconSrc: TestImages.iconPpt,
          width: 144
        },
        {
          name: 'New Contoso Collaboration for Conference Presentation Draft',
          linkProps: {
            href: 'http://bing.com',
            target: '_blank'
          },
          previewImageSrc: TestImages.documentPreviewTwo,
          iconSrc: TestImages.iconPpt,
          width: 144
        },
        {
          name: 'Spec Sheet for design',
          linkProps: {
            href: 'http://bing.com',