def get(self, key: TKey, default=None) -> cirq.Pauli | TDefault | None:
        """Returns the `cirq.Pauli` operation acting on qubit `key` or `default` if none exists."""
        result = self.pauli_int_dict.get(key, None)
        return default if result is None else _INT_TO_PAULI[result - 1]
Returns the `cirq.Pauli` operation acting on qubit `key` or `default` if none exists.
cirq-core/cirq/ops/pauli_string.py