How to use the lib0/encoding.js.writeVarUint8Array function in lib0

this.peer.on('connect', () => {
      log('connected to ', logging.BOLD, remotePeerId)
      this.connected = true
      // send sync step 1
      const provider = room.provider
      const doc = provider.doc
      const awareness = room.awareness
      const encoder = encoding.createEncoder()
      encoding.writeVarUint(encoder, messageSync)
      syncProtocol.writeSyncStep1(encoder, doc)
      sendWebrtcConn(this, encoder)
      const awarenessStates = awareness.getStates()
      if (awarenessStates.size > 0) {
        const encoder = encoding.createEncoder()
        encoding.writeVarUint(encoder, messageAwareness)
        encoding.writeVarUint8Array(encoder, awarenessProtocol.encodeAwarenessUpdate(awareness, Array.from(awarenessStates.keys())))
        sendWebrtcConn(this, encoder)
      }
    })
    this.peer.on('close', () => {

encoding.writeVarUint(encoderSync, messageSync)
    syncProtocol.writeSyncStep1(encoderSync, this.doc)
    broadcastBcMessage(this, encoding.toUint8Array(encoderSync))
    // broadcast local state
    const encoderState = encoding.createEncoder()
    encoding.writeVarUint(encoderState, messageSync)
    syncProtocol.writeSyncStep2(encoderState, this.doc)
    broadcastBcMessage(this, encoding.toUint8Array(encoderState))
    // write queryAwareness
    const encoderAwarenessQuery = encoding.createEncoder()
    encoding.writeVarUint(encoderAwarenessQuery, messageQueryAwareness)
    broadcastBcMessage(this, encoding.toUint8Array(encoderAwarenessQuery))
    // broadcast local awareness state
    const encoderAwarenessState = encoding.createEncoder()
    encoding.writeVarUint(encoderAwarenessState, messageAwareness)
    encoding.writeVarUint8Array(encoderAwarenessState, awarenessProtocol.encodeAwarenessUpdate(this.awareness, [this.doc.clientID]))
    broadcastBcMessage(this, encoding.toUint8Array(encoderAwarenessState))
  }
  disconnect () {

).then(cipher => {
    const encryptedDataEncoder = encoding.createEncoder()
    encoding.writeVarString(encryptedDataEncoder, 'AES-GCM')
    encoding.writeVarUint8Array(encryptedDataEncoder, iv)
    encoding.writeVarUint8Array(encryptedDataEncoder, new Uint8Array(cipher))
    return encoding.toUint8Array(encryptedDataEncoder)
  })
}

write (encoder, offset) {
    super.write(encoder, offset, structBinaryRefNumber)
    encoding.writeVarUint8Array(encoder, this.content)
  }
}

).then(cipher => {
    const encryptedDataEncoder = encoding.createEncoder()
    encoding.writeVarString(encryptedDataEncoder, 'AES-GCM')
    encoding.writeVarUint8Array(encryptedDataEncoder, iv)
    encoding.writeVarUint8Array(encryptedDataEncoder, new Uint8Array(cipher))
    return encoding.toUint8Array(encryptedDataEncoder)
  })
}