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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 previous(self, type=None):
 """ Returns the next previous word in the sentence with the given type. """

        i = self.index - 1
        s = self.sentence
        while i > 0:
            if type in (s[i].type, None):
                return s[i]
            i -= 1