**Input**: A qubit in state $|\psi\rangle = \alpha |0\rangle + \beta |1\rangle$.

**Goal**: Change the state of the qubit as follows:

- If the qubit is in state $|0\rangle$, change its state to $|+\rangle = \frac{1}{\sqrt{2}} \big(|0\rangle + |1\rangle\big)$.
- If the qubit is in state $|1\rangle$, change its state to $|-\rangle = \frac{1}{\sqrt{2}} \big(|0\rangle - |1\rangle\big)$.
- If the qubit is in superposition, change its state according to the effect on basis vectors.
