def mutable_copy(self) -> MutableDensePauliString:
        """A `cirq.MutableDensePauliString` with the same contents."""
        return MutableDensePauliString(
            coefficient=self.coefficient, pauli_mask=np.copy(self.pauli_mask)
        )
A `cirq.MutableDensePauliString` with the same contents.
cirq-core/cirq/ops/dense_pauli_string.py