**##############################################################**
commands and arguments 
start-session hostname                                   - Start a new session
check_out DocumentUID                                    - Get file
check_in DocumentUID SecurityFlag                        - Push file
delegate DocumentUID Client Time PropagationFlag         - Doing Delegation
safe_delete DocumentUID                                  - Doing Delegation
end-session                                              - end the session
**##############################################################**

start-session localhost
check_in test1.txt NONE
check_in test2.txt INTEGRITY
check_in test3.txt CONFIDENTIALITY
check_out test1.txt
check_out test2.txt
check_out test3.txt
delegate test1.txt Luoyin2 10000 true
delegate test2.txt Luoyin2 10000 true
delegate test3.txt Luoyin2 10000 false
safe_delete test2.txt
end-session
quit

start-session localhost
check_out test1.txt
check_out test2.txt
check_out test3.txt
delegate test1.txt Luoyin3 10000 true
delegate test3.txt Luoyin3 10000 false
end-session
quit

start-session localhost
check_out test1.txt
check_out test3.txt
end-session
quit

(1)start-session: check three terminal's first command
(2)check_in: check the result of the first terminal and the server file_system folder 
(3)check_out: check the result of the first terminal and the folder and the second terminal and the folder
(4)delegate: check the second and third terminal to check if the delegation works
(5)safe_delete: check the second terminal's `check_out test2.txt` result