import qiskit.extensions.simulator      # access simulator-specific commands
bell_circ.snapshot('1')                 # save this snapshot in slot '1'
ghz_circ = bell_circ + cnot_circ        # do other things after the snapshot
result = execute(ghz_circ, 'local_statevector_simulator').result()
result.get_snapshot('1')                # retrieve the snapshot from slot '1'