input: Write a function to find words with at least four vowels.
  assert find_words_with_four_vowels(["algorithm", "machine", "programming", "beast"]) == []
  assert find_words_with_four_vowels(["education", "beautiful", "sequence", "umbrella"]) == ["education", "beautiful", "sequence"]
  assert find_words_with_four_vowels(["hello", "world", "python", "developer"]) == []
output: def find_words_with_four_vowels(words):
      vowels = set('aeiou')
      result = []
      for word in words:
          if sum(1 for char in word if char in vowels) >= 4:
              result.append(word)
      return result