How to use the tinode-sdk.Drafty.attachFile function in tinode-sdk

if (e.target.files && e.target.files.length > 0) {
      const file = e.target.files[0];
      if (file.size > MAX_EXTERN_ATTACHMENT_SIZE) {
        // Too large.
        this.props.onError(formatMessage(messages.file_attachment_too_large,
            {size: bytesToHumanSize(file.size), limit: bytesToHumanSize(MAX_EXTERN_ATTACHMENT_SIZE)}), 'err');
      } else if (file.size > MAX_INBAND_ATTACHMENT_SIZE) {
        // Too large to send inband - uploading out of band and sending as a link.
        const uploader = this.props.tinode.getLargeFileHelper();
        if (!uploader) {
          this.props.onError(formatMessage(messages.cannot_initiate_upload));
          return;
        }
        // Format data and initiate upload.
        const uploadCompletionPromise = uploader.upload(file);
        const msg = Drafty.attachFile(null, file.type, null, file.name, file.size, uploadCompletionPromise);
        // Pass data and the uploader to the TinodeWeb.
        this.props.sendMessage(msg, uploadCompletionPromise, uploader);
      } else {
        // Small enough to send inband.
        fileToBase64(file,
          (mime, bits, fname) => {
            this.props.sendMessage(Drafty.attachFile(null, mime, bits, fname));
          },
          this.props.onError
        );
      }
    }
    // Clear the value so the same file can be uploaded again.
    e.target.value = '';
  }

(mime, bits, fname) => {
        this.props.sendMessage(Drafty.attachFile(null, mime, bits, fname));
      },
      this.props.onError)) {