function _validateArgs(uri, options, callback) {
  if (typeof options === 'function' && callback == null) {
    throw new MongooseError('Connection.prototype.openUri() no longer accepts a callback');
  } else if (typeof callback === 'function') {
    throw new MongooseError('Connection.prototype.openUri() no longer accepts a callback');
  }
}
Listen to a event once in the Connection

@param {String} event The event to listen on
@param {Function} callback
@see Connection#readyState https://mongoosejs.com/docs/api/connection.html#Connection.prototype.readyState

@method once
@instance
@memberOf Connection
@api public