function getWatcherCount(firebase, event, path, queryId) {
  const id =
    queryId || getQueryIdFromPath(path, event) || getWatchPath(event, path)
  return firebase._.watchers[id]
}
@private
@param {object} firebase - Internal firebase object
@param {string} event - Type of event to watch for
@param {string} path - Path to watch with watcher
@param {string} queryId - Id of query
@returns {number} watcherCount