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.
  import collections
  
  def top_5_frequent_words(sentence):
      if sentence == "":
          return []
      
      words = sentence.split()
      counter = collections.Counter(words)
      result = counter.most_common(5)
      return result
  
  assert top_5_frequent_words("Python is an interpreted, high-level, general-purpose programming language.") == [('Python', 1), ('is', 1), ('an', 1), ('interpreted,', 1), ('high-level,', 1)]
  assert top_5_frequent_words("The quick brown fox jumps over the lazy dog.") == [('The', 1), ('quick', 1), ('brown', 1), ('fox', 1), ('jumps', 1)]
  assert top_5_frequent_words("") == []
  assert top_5_frequent_words("a a a b b c c c c d d d d d") == [('d', 5), ('c', 4), ('a', 3), ('b', 2), ('d', 1)]
  assert top_5_frequent_words("a a a a a a a a a") == [('a', 9)]
output: if sentence == "":
      return []
  
  words = sentence.split()
  counter = collections.Counter(words)
  result = counter.most_common(5)
  return result