<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def probability_gt(self, x):
 """ Returns the probability of a random variable being greater than the given value. """

        if self.mean is None:
            return
        p = normdist(x=x, mu=self.mean, sigma=self.standard_deviation)
        return 1-p