https://rust-random.github.io/book/guide-rngs.html#basic-pseudo-random-number-generators-prngs https://rust-lang-nursery.github.io/rust-cookbook/algorithms/randomness.html https://docs.rs/rand/0.7.2/rand/trait.SeedableRng.html https://rust-random.github.io/book/guide-dist.html https://rust-random.github.io/rand/rand/distributions/weighted/struct.WeightedIndex.html
https://rust-random.github.io/book/guide-rngs.html#basic-pseudo-random-number-generators-prngs
https://rust-lang-nursery.github.io/rust-cookbook/algorithms/randomness.html
https://docs.rs/rand/0.7.2/rand/trait.SeedableRng.html
https://rust-random.github.io/book/guide-dist.html
https://rust-random.github.io/rand/rand/distributions/weighted/struct.WeightedIndex.html