'Set the scope to be used in token requests
:param scope: scope to be used. If the scope is different, clear caches'

@scope.setter
def scope(self, value):

    if (value not in self.SCOPES):
        raise exceptions.InvalidScope(scope=value, auth_provider=self.__class__.__name__)
    if (value != self.scope):
        self.clear_auth()
        self._scope = value
