input: Write a function to print the top 5 most frequent words in a given sentence. If the sentence is empty, return an empty list.
  def top_5_frequent_words(sentence):
      if not sentence:
          return []
      words = sentence.split()
      counter = collections.Counter(words)
      return counter.most_common(5)
  
  assert top_5_frequent_words("Python is an interpreted, high-level, general-purpose programming language.")==[('programming', 1), ('language.', 1), ('general-purpose', 1), ('high-level,', 1), ('interpreted,', 1)]
  
  assert top_5_frequent_words("Python Python is is an an an interpreted, high-level, general-purpose programming language.")==[('an', 3), ('is', 2), ('Python', 2), ('interpreted,', 1), ('high-level,', 1)]
  
  assert top_5_frequent_words("")==[]
output: def top_5_frequent_words(sentence):
      if not sentence:
          return []
      words = sentence.split()
      counter = collections.Counter(words)
      return counter.most_common(5)