def _decompose_multi_qubit_operation(
        self, op: cirq.Operation, moment_idx: int
    ) -> DecomposeResult:
        """Decomposes operations acting on more than 2 qubits using gates from this gateset.

        Args:
            op: A multi qubit (>2q) operation.
            moment_idx: Index of the moment in which operation `op` occurs.

        Returns:
            A `cirq.OP_TREE` implementing `op` using gates from this gateset OR
            None or NotImplemented if decomposition of `op` is unknown.
        """
        return NotImplemented
Decomposes operations acting on more than 2 qubits using gates from this gateset.

        Args:
            op: A multi qubit (>2q) operation.
            moment_idx: Index of the moment in which operation `op` occurs.

        Returns:
            A `cirq.OP_TREE` implementing `op` using gates from this gateset OR
            None or NotImplemented if decomposition of `op` is unknown.
        
cirq-core/cirq/transformers/target_gatesets/compilation_target_gateset.py