def __init__(self, executables: Sequence[QuantumExecutable]):
        """Initialize and normalize the quantum executable group.

        Args:
             executables: A sequence of `cg.QuantumExecutable` which will be frozen into a
                tuple.
        """

        if not isinstance(executables, tuple):
            executables = tuple(executables)
        object.__setattr__(self, 'executables', executables)

        # Ensure the object is hashable at construction time.
        object.__setattr__(self, '_hash', None)
        _ = hash(self)
Initialize and normalize the quantum executable group.

        Args:
             executables: A sequence of `cg.QuantumExecutable` which will be frozen into a
                tuple.
        
cirq-google/cirq_google/workflow/quantum_executable.py