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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _normalize_string(raw_str):
 """Normalizes the string using tokenizer.encode. Args: raw_str: the input string Returns: A string which is ready to be tokenized using split() """

  return " ".join(
      token.strip()
      for token in tokenizer.encode(text_encoder.native_to_unicode(raw_str)))