Helper function to get results for a single cross-validation fold

.get_one_fold(x, sens, gn, quantile_type = 8, ...)

Arguments

x	An entry in prediction_list.
sens	The sensitivity constraint.
gn	An estimate of the marginal probability that `Y = 1`.
quantile_type	The type of quantile estimate to use.
...	Other options (not currently used)