input: Write a function to create an autocomplete system that predicts words based on the input text. The function should generate word candidates from the input text, filter them, rank them, and return the top 5 suggestions. If the input text is empty, it should return an empty list.
  
  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]
  
  assert autocomplete("Hel") == ["Hello", "Help", "Helper", "Helmet", "Helicopter"]
  assert autocomplete("Pro") == ["Program", "Project", "Progress", "Problem", "Production"]
  assert autocomplete("") == []
  assert autocomplete("A") == ["Apple", "Application", "Approval", "Argument", "Arrow"]
  assert autocomplete("De") == ["Development", "Design", "Decide", "Demonstrate", "Determine"]
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]