<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def prepare(self, cache):
 """Prepare to run next shot."""

        if cache is not None:
            np.copyto(self.qubits, cache)
        else:
            self.qubits.fill(0.0)
            self.qubits[0] = 1.0
        self.cregs = [0] * self.n_qubits