* Codercise H.7.3.* Use the PREPARE and SELECT procedures you defined above to generate superpositions of two-qubit computational basis states,

```
U_list = [np.kron(qml.PauliZ.matrix, qml.PauliZ.matrix), np.kron(qml.PauliZ.matrix,qml.PauliX.matrix), np.kron(qml.PauliX.matrix,qml.PauliZ.matrix), np.kron(qml.PauliX.matrix,qml.PauliX.matrix)]
qml.QubitUnitary(PREPARE(beta_list**2), wires=aux)
SELECT(U_list)
return qml.state()
beta_list = np.array([1, 0, 0, 1])
normalized_coefficients = [quantum_memory(beta_list)[i].item() for i in range(0, 20, 5)]
print("The amplitudes on the main register are proportional to", normalized_coefficients, ".")
```

Error: unsupported operand type(s) for *: ‘function’ and ‘function’

I don’t understand why this error is there?