g.err = err
				if g.cancel != nil {
					g.cancel(g.err)
				}
			})
		}
	}()
}

// TryGo calls the given function in a new goroutine only if the number of
// active goroutines in the group is currently below the configured limit.
//
// The return value reports whether the goroutine was started.
func (g *Group) TryGo(f func() error) bool {
	if g.sem != nil {
		select {
		case g.sem <- token{}: