It is important that the machine contains a high-quality RNG implementation. Because all PRNGs must eventually repeat their number sequence and, if the period is short or the PRNG is otherwise flawed, an advanced player may be able to "predict" the next result. Having access to the PRNG code and seed values, Ronald Dale Harris, a former slot machine programmer, discovered equations for specific gambling games like Keno that allowed him to predict what the next set of selected numbers would be based on the previous games played.