human
Solve the following python programming problem given the following code:
def _loginTest(self, opt) : 
    '
        This method executes both positive and negative authentication
        tests against whatever credentials checker has been stored in
        the Options class.

        @param opt: An instance of L{tap.Options}.
        ' 
    self.assertEquals (len (opt ['credCheckers']), 1) 
    checker = opt ['credCheckers'] [0] 
    self.assertFailure (checker.requestAvatarId (checker.joeWrong), error.UnauthorizedLogin) 
    def _gotAvatar(username) : 
        self.assertEquals (username, self.admin.username) 
return checker.requestAvatarId (self.admin).addCallback (_gotAvatar) 

    
    

    Fix the buggy line: self.assertFailure (checker.requestAvatarId (checker.joeWrong), error.UnauthorizedLogin)
assistant
#Here is Python code to fix the buggy line: self.

self.assertFailure (checker.requestAvatarId (self.joeWrong), error.UnauthorizedLogin)