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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 tokenize(self, tokenizer=None):
 """Return a list of tokens, using ``tokenizer``. :param tokenizer: (optional) A tokenizer object. If None, defaults to this blob's default tokenizer. """

        t = tokenizer if tokenizer is not None else self.tokenizer
        return WordList(t.tokenize(self.raw))