def _has_kraus_(self) -> bool:
        """Returns True if self has a Kraus representation and self uses <= 10 qubits."""
        return (
            all(protocols.has_kraus(op) for op in self.operations) and len(self._qubit_to_op) <= 10
        )
Returns True if self has a Kraus representation and self uses <= 10 qubits.
cirq-core/cirq/circuits/moment.py