Posix return or exit

[M.N.A.Smadi]

hi;
my script must return codes which are based on the POSIX spec of 
returning a positive value.  A work perl version of my code uses 
exit(code_num).  I am not sure if the equivilant in python is also:
     exit(code_num)
or
    return code_num

any ideas?

thanks
moe smadi