docs: function statFile(filePath, callback) {
    fs.stat(filePath, function(err, stats) {
  
      // Resource does not exist
      if (err && (err.code === 'ENOENT' || err.code === 'ENOTDIR')) {
        const error = new Error('Resource does not exist');
        error.httpCode = 404;
  
        callback(error);
  
      // Not a file
      } else if (!stats.isFile()) {
        const error = new Error('Resource is not a file');
        error.httpCode = 400;
  
        callback(error);
  
      // Server error
      } else if (err) {
        const error = new Error('Server error');
        error.httpCode = 500;
  
        callback(error);
  
      // Success. Get the stats.
      } else {
        callback(null, stats);
      }
    });
  }