input: Write a function named autocomplete that takes an input text and returns a list of the top 5 predicted words based on the input text. The function should generate word candidates, filter and rank them, and return the top 5 words.
  
  Here is the function header:
  
  def autocomplete(input_text):
      # Generate the word candidates
      word_candidates = generate_candidates(input_text)
      # Filter the word candidates 
      filtered_words = filter_candidates(word_candidates)
      # Rank the words and return the top 5 
      sorted_words = rank_words(filtered_words)
      return sorted_words[:5]
  
  Here are the assert test cases:
  
  assert autocomplete("hel") == ["help", "hello", "held", "hell", "helm"]
  assert autocomplete("app") == ["apple", "application", "appear", "appetite", "appendix"]
  assert autocomplete("co") == ["come", "coffee", "common", "company", "complete"]
  assert autocomplete("z") == ["zero", "zone", "zoo", "zone", "zip"]
  assert autocomplete("") == []
output: def autocomplete(input_text):
      word_candidates = generate_candidates(input_text)
      filtered_words = filter_candidates(word_candidates)
      sorted_words = rank_words(filtered_words)
      return sorted_words[:5]