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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 raw_diff(self):
 """ Returns raw string as udiff """

        udiff_copy = self.copy_iterator()
        if self.__format == 'gitdiff':
            udiff_copy = self._parse_gitdiff(udiff_copy)
        return u''.join(udiff_copy)