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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 sanitize_words(self, words):
 """Guarantees that all textual symbols are unicode. Note: We do not convert numbers, only strings to unicode. We assume that the strings are encoded in utf-8. """

    _words = []
    for w in words:
      if isinstance(w, string_types) and not isinstance(w, unicode):
        _words.append(unicode(w, encoding="utf-8"))
      else:
        _words.append(w)
    return _words