human
Solve the following python programming problem given the following code:
def testMethodNotFound(self) : 
    '
        Check that a non existing method return error 500.
        ' 
    d = self.proxy ().callRemote ('doesntexist') 
    self.assertFailure (cb, error.Error) 
    def cb(err) : 
        self.assertEquals (int (err.status), 500) 
d.addCallback (cb) 
    return d 

    
    

    Fix the buggy line: self.assertFailure (cb, error.Error)
assistant
#Here is Python code to fix the buggy line: self.

self.assertFailure (d, error.Error)