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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 bind(self, container):
 """ Bind implementation that supports sharing. """

        # if there's already a matching bound instance, return that
        shared = container.shared_extensions.get(self.sharing_key)
        if shared:
            return shared

        instance = super(SharedExtension, self).bind(container)

        # save the new instance
        container.shared_extensions[self.sharing_key] = instance

        return instance