code: function getSignature ({
    params,
    accessKeySecret
  }) {
    const paramString = paramsToString(params)
    const stringToSign = `POST&${encodeURIComponent('/')}&${encodeURIComponent(paramString)}`
  
    return crypto
      .createHmac('sha1', `${accessKeySecret}&`)
      .update(stringToSign)
      .digest('base64')
  }
docs: /* ----------
  get signature