How to use the @sourcegraph/codeintellify/lib/helpers.propertyIsDefined function in @sourcegraph/codeintellify

this.setState({ site })
                },
                () => {
                    this.setState({ site: undefined })
                }
            )
        )

        this.subscriptions.add(
            // Ensure the site is valid.
            fetchingSite
                .pipe(
                    // Get the access token for this server if we have it.
                    switchMap(() => getAccessToken(sourcegraphUrl)),
                    switchMap(token => fetchCurrentUser(false).pipe(map(user => ({ user, token })))),
                    filter(propertyIsDefined('user')),
                    // Get the IDs for all access tokens for the user.
                    switchMap(({ token, user }) =>
                        fetchAccessTokenIDs(user.id).pipe(map(usersTokenIDs => ({ usersTokenIDs, user, token })))
                    ),
                    // Make sure the token still exists on the server. If it
                    // does exits, use it, otherwise create a new one.
                    switchMap(({ user, token, usersTokenIDs }) => {
                        const tokenExists = token && usersTokenIDs.map(({ id }) => id).includes(token.id)

                        return token && tokenExists
                            ? of(token)
                            : createAccessToken(user.id).pipe(
                                  tap(createdToken => {
                                      setAccessToken(sourcegraphUrl, createdToken)
                                  })
                              )

props.setSourcegraphURL(url)
            })
        )

        this.subscriptions.add(
            // Ensure the site is valid.
            fetchingSite
                .pipe(
                    filter(urlOrError => !isErrorLike(urlOrError)),
                    map(urlOrError => urlOrError as string),
                    // Get the access token for this server if we have it.
                    switchMap(url => this.props.getAccessToken(url).pipe(map(token => ({ token, url })))),
                    switchMap(({ url, token }) =>
                        this.props.fetchCurrentUser(false).pipe(map(user => ({ user, token, url })))
                    ),
                    filter(propertyIsDefined('user')),
                    // Get the IDs for all access tokens for the user.
                    switchMap(({ token, user, url }) =>
                        this.props
                            .fetchAccessTokenIDs(user.id)
                            .pipe(map(usersTokenIDs => ({ usersTokenIDs, user, token, url })))
                    ),
                    // Make sure the token still exists on the server. If it
                    // does exits, use it, otherwise create a new one.
                    switchMap(({ user, token, usersTokenIDs, url }) => {
                        const tokenExists = token && usersTokenIDs.map(({ id }) => id).includes(token.id)

                        return token && tokenExists
                            ? of(token)
                            : this.props.createAccessToken(user.id).pipe(this.props.setAccessToken(url))
                    })
                )

const fetchJumpURL = createJumpURLFetcher(
        simpleProviderFns.fetchDefinition,
        codeHost.buildJumpURLLocation || toPrettyBlobURL
    )

    const containerComponentUpdates = new Subject()

    const hoverifier = createHoverifier({
        closeButtonClicks,
        goToDefinitionClicks,
        hoverOverlayElements,
        hoverOverlayRerenders: containerComponentUpdates.pipe(
            withLatestFrom(hoverOverlayElements),
            map(([, hoverOverlayElement]) => ({ hoverOverlayElement, relativeElement })),
            filter(propertyIsDefined('hoverOverlayElement'))
        ),
        pushHistory: path => {
            location.href = path
        },
        fetchHover: ({ line, character, part, ...rest }) =>
            simpleProviderFns
                .fetchHover({ ...rest, position: { line, character } })
                .pipe(map(hover => (hover ? (hover as HoverMerged) : hover))),
        fetchJumpURL,
        getReferencesURL: position => toPrettyBlobURL({ ...position, position, viewState: 'references' }),
        logTelemetryEvent: () => eventLogger.logCodeIntelligenceEvent(),
    })

    const Link: LinkComponent = ({ to, children, ...rest }) => (
        <a href="{new">
            {children}</a>

const fetchJumpURL = createJumpURLFetcher(
        simpleProviderFns.fetchDefinition,
        codeHost.buildJumpURLLocation || toPrettyBlobURL
    )

    const containerComponentUpdates = new Subject()

    const hoverifier = createHoverifier({
        closeButtonClicks,
        goToDefinitionClicks,
        hoverOverlayElements,
        hoverOverlayRerenders: containerComponentUpdates.pipe(
            withLatestFrom(hoverOverlayElements),
            map(([, hoverOverlayElement]) => ({ hoverOverlayElement, relativeElement })),
            filter(propertyIsDefined('hoverOverlayElement'))
        ),
        pushHistory: path => {
            location.href = path
        },
        fetchHover: ({ line, character, part, ...rest }) =>
            simpleProviderFns
                .fetchHover({ ...rest, position: { line, character } })
                .pipe(map(hover => (hover ? (hover as HoverMerged) : hover))),
        fetchJumpURL,
        logTelemetryEvent: () => eventLogger.logCodeIntelligenceEvent(),
    })

    const Link: LinkComponent = ({ to, children, ...rest }) => (
        <a href="{new">
            {children}
        </a>

let githubState: GitHubBlobUrl | undefined
            for (const anchor of anchors) {
                const anchorState = getGitHubState(anchor.href) as GitHubBlobUrl
                if (anchorState) {
                    githubState = anchorState
                    break
                }
            }

            return githubState
        }),
        filter(isDefined),
        filter(propertyIsDefined('owner')),
        filter(propertyIsDefined('repoName')),
        filter(propertyIsDefined('rev')),
        filter(propertyIsDefined('filePath')),
        map(({ owner, repoName, ...rest }) => ({ repoPath: `${window.location.host}/${owner}/${repoName}`, ...rest })),
        switchMap(({ repoPath, rev, ...rest }) =>
            resolveRev({ repoPath, rev }).pipe(
                retryWhenCloneInProgressError(),
                map(commitID => ({ ...rest, repoPath, commitID, rev: rev || commitID }))
            )
        )
    )

map(codeView => {
            const anchors = codeView.getElementsByTagName('a')
            let githubState: GitHubBlobUrl | undefined
            for (const anchor of anchors) {
                const anchorState = getGitHubState(anchor.href) as GitHubBlobUrl
                if (anchorState) {
                    githubState = anchorState
                    break
                }
            }

            return githubState
        }),
        filter(isDefined),
        filter(propertyIsDefined('owner')),
        filter(propertyIsDefined('repoName')),
        filter(propertyIsDefined('rev')),
        filter(propertyIsDefined('filePath')),
        map(({ owner, repoName, ...rest }) => ({ repoPath: `${window.location.host}/${owner}/${repoName}`, ...rest })),
        switchMap(({ repoPath, rev, ...rest }) =>
            resolveRev({ repoPath, rev }).pipe(
                retryWhenCloneInProgressError(),
                map(commitID => ({ ...rest, repoPath, commitID, rev: rev || commitID }))
            )
        )
    )

export const resolveFileInfo = (codeView: HTMLElement): Observable =>
    of(undefined).pipe(
        map(() => {
            const { repoPath, filePath, rev } = getFilePageInfo()

            return { repoPath, filePath, rev }
        }),
        filter(propertyIsDefined('filePath')),
        switchMap(({ repoPath, rev, ...rest }) =>
            resolveRev({ repoPath, rev }).pipe(
                retryWhenCloneInProgressError(),
                map(commitID => ({ ...rest, repoPath, commitID, rev: rev || commitID }))
            )
        )
    )