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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 add_grant(self, grant):
 """ Adds a Grant that the provider should support. :param grant: An instance of a class that extends :class:`oauth2.grant.GrantHandlerFactory` :type grant: oauth2.grant.GrantHandlerFactory """

        if hasattr(grant, "expires_in"):
            self.token_generator.expires_in[grant.grant_type] = grant.expires_in

        if hasattr(grant, "refresh_expires_in"):
            self.token_generator.refresh_expires_in = grant.refresh_expires_in

        self.grant_types.append(grant)