from qiskit import QuantumCircuit
from qiskit.quantum_info import Statevector
qc = QuantumCircuit(3)
qc.h(0)                 # illustrative unknown logical superposition
qc.cx(0, 1); qc.cx(0, 2)  # encode alpha|000>+beta|111>
qc.x(1)                 # inject bit-flip error on middle qubit
print(qc.draw())
print(Statevector.from_instruction(qc).probabilities_dict())
# Error syndrome would be extracted with ancillas in a full QEC circuit.