code: function exists(filepath) {
    const cached = existsCache.has(filepath);
  
    // Only return positive to allow for generated files
    if (cached) return true;
  
    const filepathExists = fs.existsSync(filepath);
  
    if (filepathExists) existsCache.add(filepath);
  
    return filepathExists;
  }
docs: Determine if 'filepath' exists
  @param {String} filepath
  @returns {Boolean}