How to use the @uppy/companion-client.RequestClient function in @uppy/companion-client

this.i18nInit()

    this.hostname = this.opts.companionUrl

    if (!this.hostname) {
      throw new Error('Companion hostname is required, please consult https://uppy.io/docs/companion')
    }

    // Bind all event handlers for referencability
    this.getMeta = this.getMeta.bind(this)
    this.addFile = this.addFile.bind(this)
    this.handleRootDrop = this.handleRootDrop.bind(this)
    this.handleRootPaste = this.handleRootPaste.bind(this)

    this.client = new RequestClient(uppy, {
      companionUrl: this.opts.companionUrl,
      companionHeaders: this.opts.companionHeaders || this.opts.serverHeaders
    })
  }

}

    const defaultOptions = {
      timeout: 30 * 1000,
      limit: 0,
      getUploadParameters: this.getUploadParameters.bind(this)
    }

    this.opts = { ...defaultOptions, ...opts }

    // i18n
    this.translator = new Translator([this.defaultLocale, this.uppy.locale, this.opts.locale])
    this.i18n = this.translator.translate.bind(this.translator)
    this.i18nArray = this.translator.translateArray.bind(this.translator)

    this.client = new RequestClient(uppy, opts)

    this.prepareUpload = this.prepareUpload.bind(this)

    this.requests = new RateLimitedQueue(this.opts.limit)
  }

constructor (uppy, opts) {
    super(uppy, opts)
    this.type = 'uploader'
    this.id = 'AwsS3Multipart'
    this.title = 'AWS S3 Multipart'
    this.client = new RequestClient(uppy, opts)

    const defaultOptions = {
      timeout: 30 * 1000,
      limit: 0,
      createMultipartUpload: this.createMultipartUpload.bind(this),
      listParts: this.listParts.bind(this),
      prepareUploadPart: this.prepareUploadPart.bind(this),
      abortMultipartUpload: this.abortMultipartUpload.bind(this),
      completeMultipartUpload: this.completeMultipartUpload.bind(this)
    }

    this.opts = Object.assign({}, defaultOptions, opts)

    this.upload = this.upload.bind(this)

    if (typeof this.opts.limit === 'number' && this.opts.limit !== 0) {