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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 ensure_security_manager(self, subject_context):
 """ Determines whether there is a ``SecurityManager`` instance in the context, and if not, adds 'self' to the context. This ensures that do_create_subject will have access to a ``SecurityManager`` during Subject construction. :param subject_context: the subject context data that may contain a SecurityManager instance :returns: the SubjectContext """

        if (subject_context.resolve_security_manager() is not None):
            msg = ("Subject Context resolved a security_manager "
                   "instance, so not re-assigning.  Returning.")
            logger.debug(msg)
            return subject_context

        msg = ("No security_manager found in context.  Adding self "
               "reference.")
        logger.debug(msg)

        subject_context.security_manager = self

        return subject_context