Return a copy of this vector with new qubits

def relabel(self, qubits: Qubits) -> 'QubitVector':
        """Return a copy of this vector with new qubits"""
        qubits = tuple(qubits)
        assert len(qubits) == self.qubit_nb
        vec = copy(self)
        vec.qubits = qubits
        return vec