def main(dbg=None, sys_argv=list(sys.argv)):
    """Routine which gets run if we were invoked directly"""
    global __title__

    # Save the original just for use in the restart that works via exec.
    orig_sys_argv = list(sys_argv)
    opts, dbg_opts, sys_argv  = process_options(__title__, __version__,
                                                sys_argv)
    dbg_opts['orig_sys_argv'] = sys_argv
    dbg_opts['interface']     = Mbullwinkle.BWInterface()
    dbg_opts['processor']     = 'bullwinkle'

    if dbg is None:
        dbg = Mdebugger.Trepan(dbg_opts)
        dbg.core.add_ignore(main)
        pass
    _postprocess_options(dbg, opts)

    # process_options has munged sys.argv to remove any options that
    # options that belong to this debugger. The original options to
    # invoke the debugger and script are in global sys_argv
    if len(sys_argv) == 0:
        # No program given to debug. Set to go into a command loop
        # anyway
        mainpyfile = None
    else:
        mainpyfile = sys_argv[0]  # Get script filename.
        if not os.path.isfile(mainpyfile):
            mainpyfile=Mclifns.whence_file(mainpyfile)
            is_readable = Mfile.readable(mainpyfile)
            if is_readable is None:
                print("%s: Python script file '%s' does not exist"
                      % (__title__, mainpyfile,))
                sys.exit(1)
            elif not is_readable:
                print("%s: Can't read Python script file '%s'"
                      % (__title__, mainpyfile,))
                sys.exit(1)
                return

        # If mainpyfile is an optimized Python script try to find and
        # use non-optimized alternative.
        mainpyfile_noopt = Mfile.file_pyc2py(mainpyfile)
        if mainpyfile != mainpyfile_noopt \
               and Mfile.readable(mainpyfile_noopt):
            print("%s: Compiled Python script given and we can't use that."
                  % __title__)
            print("%s: Substituting non-compiled name: %s" % (
                __title__, mainpyfile_noopt,))
            mainpyfile = mainpyfile_noopt
            pass

        # Replace trepan's dir with script's dir in front of
        # module search path.
        sys.path[0] = dbg.main_dirname = os.path.dirname(mainpyfile)

    # XXX If a signal has been received we continue in the loop, otherwise
    # the loop exits for some reason.
    dbg.sig_received = False

    # if not mainpyfile:
    #     print('For now, you need to specify a Python script name!')
    #     sys.exit(2)
    #     pass

    while True:

        # Run the debugged script over and over again until we get it
        # right.

        try:
            if dbg.program_sys_argv and mainpyfile:
                normal_termination = dbg.run_script(mainpyfile)
                if not normal_termination: break
            else:
                dbg.core.execution_status = 'No program'
                dbg.core.processor.process_commands()
                pass

            dbg.core.execution_status = 'Terminated'
            dbg.intf[-1].msg("The program finished - quit or restart")
            dbg.core.processor.process_commands()
        except Mexcept.DebuggerQuit:
            break
        except Mexcept.DebuggerRestart:
            dbg.core.execution_status = 'Restart requested'
            if dbg.program_sys_argv:
                sys.argv = list(dbg.program_sys_argv)
                part1 = ('Restarting %s with arguments:' %
                         dbg.core.filename(mainpyfile))
                args  = ' '.join(dbg.program_sys_argv[1:])
                dbg.intf[-1].msg(Mmisc.wrapped_lines(part1, args,
                                                     dbg.settings['width']))
            else: break
        except SystemExit:
            # In most cases SystemExit does not warrant a post-mortem session.
            break
        pass

    # Restore old sys.argv
    sys.argv = orig_sys_argv
    return
Routine which gets run if we were invoked directly