<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def T_sigma(self, sigma):
 """ Given a policy `sigma`, return the T_sigma operator. Parameters sigma : array_like(int, ndim=1) Policy vector, of length n. Returns ------- callable The T_sigma operator. """

        R_sigma, Q_sigma = self.RQ_sigma(sigma)
        return lambda v: R_sigma + self.beta * Q_sigma.dot(v)