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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 extend(self, definitions):
 """ Add several definitions at once. Existing definitions are replaced silently. :param definitions: The names and definitions. :type definitions: a :term:`mapping` or an :term:`iterable` with two-value :class:`tuple` s """

        for name, definition in dict(definitions).items():
            self.add(name, definition)