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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 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