Causes an exit from the running process.
integer, must be nonvar
Exit status code. Only the lower 8 bits of this value is used.
Causes an exit from the running process with exit code ExitCode. ExitCode defaults to zero which, by convention, signifies a successful exit from the process.
halt/[0,1] is implemented by raising a reserved exception, which is handled
at the top level; see ref-ere-int.
ExitCode is uninstantiated.
ExitCode is not an integer.