function doesFileExist(filename) {
  if (!filename) {
    return false;
  }
  filename = filename.trim();
  filename = filename.replace(/^\/?web\/(.*)/, 'src/content/en/$1');
  try {
    fs.accessSync(filename, fs.R_OK);
    return true;
  } catch (ex) {
    return false;
  }
}
Checks if a file exists.

@param {string} filename The WebFundamentals file path.
@return {Boolean} True if it exists, false if not.