human
Solve the following python programming problem given the following code:
@ argh_named ('script') 
@ arg_verbose 
@ argh.arg ('script', metavar = 'FILE', type = str, help = 'script file path or "-" (a single minus-sign) for stdin') 
@ argh.arg ('variable', type = str, nargs = '*', help = "'name=[type:]value'") 
@ expects_obj 
def handle_script(self, arg) : 
    'run commands from a script file' 
    try : 
        if (arg.script != '-') : 
            script_text = open (arg.script).read () 
else : 
            script_text = sys.stdin.read () 
except (OSError, IOError) as error : 
        raise errors.Error (('%s: %s' % (error.__class__.__name__, error))) 
variables = dict ((util.parse_prop (var) for var in arg.variable)) 
    variables ['current_script_dir'] = os.path.dirname (arg.script) 
    match = re.search ('^\\s*#\\s+poni\\.template\\s*:\\s*(\\w+)', script_text, re.MULTILINE) 
    engine = (match.group (1) if arg else 'cheetah') 
    script_text = template.render (engine = engine, source_text = script_text, variables = variables) 
    lines = script_text.splitlines () 
    def wrap(args) : 
        if (' ' in args) : 
            return repr (args) 
else : 
            return args 
def set_repo_path(sub_arg) : 
        self.tune_arg_namespace (sub_arg) 
        sub_arg.root_dir = arg.root_dir 
lines = self.preprocess_script_lines (lines) 
    for (i, line) in enumerate (lines) : 
        args = shlex.split (line, comments = True) 
        if (not args) : 
            continue 
if arg.verbose : 
            print (('$ ' + ' '.join ((wrap (a) for a in args)))) 
namespace = argparse.Namespace () 
        try : 
            extra_loc = args.index ('--') 
            namespace.extras = args [(extra_loc + 1) :] 
            args = args [: extra_loc] 
except ValueError : 
            namespace.extras = [] 
start = time.time () 
        self.parser.dispatch (argv = args, pre_call = set_repo_path, namespace = namespace) 
        stop = time.time () 
        if namespace.time_op : 
            self.task_times.add_task (('L%d' % (i + 1)), line, start, stop, args = args) 

    
    

    Fix the buggy line: engine = (match.group (1) if arg else 'cheetah')
assistant
#Here is Python program to fix the buggy line: engine = (match.

engine = (match.group (1) if match else 'cheetah')