code: function hashOfConfigFor(configHelper, filename) {
      const config = configHelper.getConfig(filename);
  
      if (!configHashCache.has(config)) {
          configHashCache.set(config, hash(`${pkg.version}_${stringify(config)}`));
      }
  
      return configHashCache.get(config);
  }
docs: Calculates the hash of the config file used to validate a given file
  @param {Object} configHelper The config helper for retrieving configuration information
  @param {string} filename The path of the file to retrieve a config object for to calculate the hash
  @returns {string} The hash of the config