atexit module lets you register termination
functions (i.e., functions to be called at program termination, last
in, first out). Termination functions are similar to clean-up
handlers established by
termination functions are globally registered and called at the end
of the whole program, while clean-up handlers are established
lexically and called at the end of a specific try
clause. Both termination functions and clean-up handlers are called
whether the program terminates normally or abnormally, but not when
the termination is caused by calling os._exit.
Module atexit supplies a single function called
Ensures that func(*args,**kwds) is called at
program termination time.