Function start_single 

pub fn start_single<'ir, 'task, B: BV, R>(
    task: Task<'ir, 'task, B>,
    shared_state: &SharedState<'ir, B>,
    collected: &R,
    collector: &Collector<'ir, B, R>,
)

Start symbolically executing a Task using just the current thread, collecting the results using the given collector.