pub fn generate<S: Strategy>(&mut self, strategy: S) -> S::Value {
        strategy
            .new_tree(&mut self.runner)
            .expect("creating a new value should succeed")
            .current()
    }
Generates a single value for this strategy.

Panics if generating the new value fails. The only situation in which this can happen is if
generating the value causes too many internal rejects.
internal-tools/proptest-ext/src/lib.rs