def __init__(
        self,
        sim_state: cirq.SimulationStateBase[cirq.StateVectorSimulationState],
        dtype: type[np.complexfloating] = np.complex64,
    ):
        """Results of a step of the simulator.

        Args:
            sim_state: The qubit:SimulationState lookup for this step.
            dtype: The `numpy.dtype` used by the simulation. One of
                `numpy.complex64` or `numpy.complex128`.
        """
        qubit_map = {q: i for i, q in enumerate(sim_state.qubits)}
        super().__init__(sim_state=sim_state, qubit_map=qubit_map)
        self._dtype = dtype
        self._state_vector: np.ndarray | None = None
Results of a step of the simulator.

        Args:
            sim_state: The qubit:SimulationState lookup for this step.
            dtype: The `numpy.dtype` used by the simulation. One of
                `numpy.complex64` or `numpy.complex128`.
        
cirq-core/cirq/sim/sparse_simulator.py