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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 register_scheme(self, scheme, cls):
 """ It is possible to inject new schemes at runtime """

        if scheme in self._schemes:
            raise DuplicateScheme()

        urlparse.register_scheme(scheme)
        # TODO (vng): verify the interface of the new class
        self._schemes[scheme] = cls