code: def rabin_karp(word, text):
      if word == "" or text == "":
          return None
      if len(word) > len(text):
          return None
  
      rolling_hash = RollingHash(text, len(word))
      word_hash = RollingHash(word, len(word))
      # word_hash.move_window()
  
      for i in range(len(text) - len(word) + 1):
          if rolling_hash.hash == word_hash.hash:
              if rolling_hash.window_text() == word:
                  return i
          rolling_hash.move_window()
      return None
  
label_desc: Use image node_id 1 for calling a global function with example usage: rabin_karp(word, text) and returns: None, None, None, i