human
Solve the following python programming problem given the following code:
def call_app(self, req, app = None, expect_exception = False) : 
    if (app is None) : 
        app = self.app 
self.authorized = [] 
    def authorize(req) : 
        self.authorized.append (req) 
if ('swift.authorize' not in req.environ) : 
        req.environ ['swift.authorize'] = authorize 
req.headers.setdefault ('User-Agent', 'Marula Kruger') 
    status = [None] 
    headers = [None] 
    def start_response(s, h, ei = None) : 
        status [0] = s 
        headers [0] = h 
body_iter = app (req.environ, status) 
    body = '' 
    caught_exc = None 
    try : 
        for chunk in body_iter : 
            body += chunk 
except Exception as exc : 
        if expect_exception : 
            caught_exc = exc 
else : 
            raise 
if expect_exception : 
        return (status [0], headers [0], body, caught_exc) 
else : 
        return (status [0], headers [0], body) 

    
    

    Fix the buggy line: body_iter = app (req.environ, status)
assistant
#Here is Python program to fix the buggy line: body_iter = app (req.

body_iter = app (req.environ, def start_response()