input: Write a function to print the top 5 most frequent words in a given sentence. If the sentence is empty, print an empty list.
  
  from collections import Counter
  
  def most_frequent_words(sentence):
      if not sentence:
          return []
      words = sentence.split()
      counter = Counter(words)
      return counter.most_common(5)
  
  assert most_frequent_words("Python is an interpreted high-level general-purpose programming language") == [('Python', 1), ('is', 1), ('an', 1), ('interpreted', 1), ('high-level', 1)]
  assert most_frequent_words("") == []
  assert most_frequent_words("the quick brown fox jumps over the lazy dog") == [('the', 2), ('quick', 1), ('brown', 1), ('fox', 1), ('jumps', 1)]
output: from collections import Counter
  
  def most_frequent_words(sentence):
      if not sentence:
          return []
      words = sentence.split()
      counter = Counter(words)
      return counter.most_common(5)