function uniqueWords(text: string): string[] {

  if(text.length === 0) return [];
  
  const dictionary: Record<string, number> = {};
  const words: string[] = text.split(/\s+/).map(w => w.toLowerCase())

  for(let word of words){
    dictionary[word] ??= 0;
    dictionary[word] += 1;
  }
  return Object.keys(dictionary).filter(w => dictionary[w] === 1);
}

// Do not modify: needed to evaluate the result.
export { uniqueWords };