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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 evolve(self, rho: Density) -> Density: """Apply the action of this Kraus quantum operation upon a density"""

        qubits = rho.qubits
        results = [op.evolve(rho) for op in self.operators]
        tensors = [rho.tensor * w for rho, w in zip(results, self.weights)]
        tensor = reduce(add, tensors)
        return Density(tensor, qubits)