How to use the pygsti.obj.ProcessorSpec function in pyGSTi

def __init__(self, gate_names: List[str] = None):
        """Construct object for randomized benchmarking for given set of supported gates.
        Args:
            gate_names : list of supported gate names
                Default: ['X', 'X90', 'Y', 'Y90']
        """
        if gate_names is None:
            gate_names = ['X', 'X90', 'Y', 'Y90']

        gst_gate_names = pygsti_utils.to_gst_gate_list(gate_names)

        self._qubit_labels = ['Q0']
        self._chip_spec = pygsti.obj.ProcessorSpec(1, gst_gate_names, availability={}, qubit_labels=self._qubit_labels)