def start_timer():
    """ Module that calculates the total time of the execution of the program.
    NB: Optionnal. If the module 'time' in not found, this will be skipped."""
    try:
        global time
        import time
        return time.time()
    except ModuleNotFoundError:
        print(
            'The module "time" was not found. The executation time of this program will not be displayed.'
            )
        return 0
