human
Solve the following python programming problem given the following code:
def _do_test_exception_mapping(self, exception_type, msg) : 
    @ webob.dec.wsgify 
    def fail(req) : 
        raise exception_type (msg) 
api = self._wsgi_app (fail) 
    resp = webob.Request.blank ('/').get_response (api) 
    self.assertIn (msg, resp.body) 
    self.assertEqual (resp.status_int, exception_type.code, resp.body) 
    if hasattr (exception_type, 'headers') : 
        for (key, value) in six.iteritems (api.headers) : 
            self.assertIn (key, resp.headers) 
            self.assertEqual (resp.headers [key], str (value)) 

    
    

    Fix the buggy line: for (key, value) in six.iteritems (api.headers) :
assistant
#Here is Python code to fix the buggy line: for (key, value) in six.

for (key, value) in six.iteritems (exception_type.headers) :