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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 preprocess(self, xs):
 """Preprocess a single example. Firstly, tokenization and the supplied preprocessing pipeline is applied. Since this field is always sequential, the result is a list. Then, each element of the list is preprocessed using ``self.nesting_field.preprocess`` and the resulting list is returned. Arguments: xs (list or str):
 The input to preprocess. Returns: list: The preprocessed list. """

        return [self.nesting_field.preprocess(x)
                for x in super(NestedField, self).preprocess(xs)]