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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _determine_ctxt(self):
 """ Validate aa-profile-mode settings is disable, enforce, or complain. :return ctxt: Dictionary of the apparmor profile or None """

        if config('aa-profile-mode') in ['disable', 'enforce', 'complain']:
            ctxt = {'aa_profile_mode': config('aa-profile-mode'),
                    'ubuntu_release': lsb_release()['DISTRIB_RELEASE']}
            if self.aa_profile:
                ctxt['aa_profile'] = self.aa_profile
        else:
            ctxt = None
        return ctxt