docs: function validateArgs (type, payload) {
    if (!type) {
      return new Error('type is required');
    }
    if (!payload) {
      return new Error('payload is required');
    }
    if (!isNumber(type)) {
      return new Error('type must be a number');
    }
    if (!isBuffer(payload) && !isString(payload)) {
      return new Error('payload must be buffer or string');
    }
    if (type > 3) {
      return new Error('type must be a number less than 3');
    }
  }