input: Write a function to create an autocomplete system that predicts words based on the input text. The function should generate word candidates, filter them, and return the top 5 ranked words.
  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("hello")==['hello', 'helloing', 'helloed', 'helloes', 'hellos']
  assert autocomplete("how")==['how', 'howdy', 'however', 'hows', 'howto']
  assert autocomplete("python")==['python', 'pythonic', 'pythonista', 'pythonize', 'pythonic']
  assert autocomplete("programming")==['programming', 'programmer', 'programs', 'programmed', 'programmatic']
  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]