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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 gen_lt(self):
 """Generate a new LoginTicket and add it to the list of valid LT for the user"""

        self.request.session['lt'] = self.request.session.get('lt', []) + [utils.gen_lt()]
        if len(self.request.session['lt']) > 100:
            self.request.session['lt'] = self.request.session['lt'][-100:]