How to use the vscode-languageserver-protocol.LocationLink.is function in vscode-languageserver-protocol

public async handleLocations(definition: Definition | LocationLink[], openCommand?: string | false): Promise {
    if (!definition) return
    let locations: Location[] = Array.isArray(definition) ? definition as Location[] : [definition]
    let len = locations.length
    if (len == 0) return
    if (len == 1 && openCommand !== false) {
      let location = definition[0] as Location
      if (LocationLink.is(definition[0])) {
        let link = definition[0] as LocationLink
        location = Location.create(link.targetUri, link.targetRange)
      }
      let { uri, range } = location
      await workspace.jumpTo(uri, range.start, openCommand)
    } else {
      await workspace.showLocations(definition as Location[])
    }
  }

public async getQuickfixItem(loc: Location | LocationLink, text?: string, type = '', module?: string): Promise {
    if (LocationLink.is(loc)) {
      loc = Location.create(loc.targetUri, loc.targetRange)
    }
    let doc = this.getDocument(loc.uri)
    let { uri, range } = loc
    let { line, character } = range.start
    let u = URI.parse(uri)
    let bufnr = doc ? doc.bufnr : -1
    if (!text && u.scheme == 'file') {
      text = await this.getLine(uri, line)
      character = byteIndex(text, character)
    }
    let item: QuickfixItem = {
      uri,
      filename: u.scheme == 'file' ? u.fsPath : uri,
      lnum: line + 1,
      col: character + 1,

public async handleLocations(definition: Definition | LocationLink[], openCommand?: string): Promise {
    if (!definition) return
    if (Array.isArray(definition)) {
      let len = definition.length
      if (len == 0) return
      if (len == 1) {
        let location = definition[0] as Location
        if (LocationLink.is(definition[0])) {
          let link = definition[0] as LocationLink
          location = Location.create(link.targetUri, link.targetRange)
        }
        let { uri, range } = location
        await workspace.jumpTo(uri, range.start, openCommand)
      } else {
        await workspace.showLocations(definition as Location[])
      }
    } else {
      let { uri, range } = definition as Location
      await workspace.jumpTo(uri, range.start, openCommand)
    }
  }