exit([arg])
Exit from Python. This is implemented by raising the SystemExit
exception, so cleanup actions specified by finally clauses of try
statements are honored, and it is possible to intercept the exit
attempt at an outer level. The optional argument arg can be an
integer giving the exit status (defaulting to zero), or another
type of object. If it is an integer, zero is considered
successful termination
and any nonzero value is considered
abnormal termination
by shells and the like. Most systems
require it to be in the range 0-127, and produce undefined results
otherwise. Some systems have a convention for assigning specific
meanings to specific exit codes, but these are generally
underdeveloped; Unix programs generally use 2 for command line
syntax errors and 1 for all other kind of errors. If another type
of object is passed, None is
equivalent to passing zero, and any other object is printed to
sys.stderr and results in an exit code of 1. In
particular, `sys.exit("some error message")` is a quick way to exit
a program when an error occurs.