code: def get_checksum(cls, phrase):
          
          phrase_split = phrase.split(" ")
          if len(phrase_split) < 12:
              raise ValueError("Invalid mnemonic phrase")
          if len(phrase_split) > 13:
              # Standard format
              phrase = phrase_split[:24]
          else:
              # MyMonero format
              phrase = phrase_split[:12]
          wstr = "".join(word[:cls.unique_prefix_length] for word in phrase)
          wstr = bytearray(wstr.encode('utf-8'))
          z = ((crc32(wstr) & 0xffffffff) ^ 0xffffffff ) >> 0
          z2 = ((z ^ 0xffffffff) >> 0) % len(phrase)
          return phrase_split[z2]
docs: Given a mnemonic word string, return a string of the computed checksum.
  
          :rtype: str