pick<T> method
Weighted pick, bridging straight to the existing weightedRandomPick
— same validation/selection algorithm, sourced from this deterministic
generator instead of dart:math's own Random. Invalid input (empty
list, mismatched lengths, a bad weight) throws before this generator's
state is touched, same as weightedRandomPick itself.
Implementation
T pick<T>(List<T> items, List<double> weights) =>
weightedRandomPick(items, weights, random: this);