is " Commands:
------------------------------------
? display this help
q Quit this simulator
T display current Time
t <i> add <i> minutes to the current time
a Arrival of a new car into the parking
d <i> Departure of the car number <i>
l <i> number of cars at Level <i>
H [<x>] display / change Hour parking price with <x>
c total Count of cars in the whole parking
------------------------------------
"
constant attribute
{}